Musharraf, who seized power in a 1999 coup but had given a conditional pledge to step down as military chief and become a civilian president this year, declared a state of emergency Saturday night, dashing recent hopes of a smooth transition to democracy for the nuclear-armed nation.
"Gen. Musharraf's second coup," said the headline in the Dawn daily. "It is martial law," said the Daily Times.
"A lot of people here are left in a state of disbelief," reports CBS News' Farhan Bokhari from Islamabad.
Authorities began rounding up opposition politicians despite calls from Washington and other Western allies not to take authoritarian measures.
Across Pakistan, police arrested political activists and lawyers at the forefront of a campaign against military rule. Among those detained were Javed Hashmi, the acting president of the party of former Prime Minister Nawaz Sharif, and Asma Jehangir, chairman of the independent Human Rights Commission of Pakistan.
U.S.-allied Musharraf removed the country's chief justice just as the Supreme Court was to rule on whether to validate his recent election as president by a largely Musharraf-friendly Parliament.
Hashmi said Musharraf usurped the independence of the judiciary "to save his own illegitimate rule."
"But he cannot survive against the people's outrage," Hashmi told reporters as he was led away with 10 aides in the central city of Multan.
Private Geo TV said in a report via satellite that authorities arrested Aitzaz Ahsan, a lawyer who represented the chief justice when Musharraf unsuccessfully tried to fire him earlier this year.
Another opposition party leader, Imran Khan, was put under house
"The only reason why he's passed the emergency is because he was scared that the Supreme Court would not allow a military general to fight the election of the president," Khan told CBS News correspondent Mark Phillips. "And what is going to happen in Pakistan is that it's going to head towards anarchy, there will be more militancy in the country."
Scores of paramilitary troops blocked access to the Supreme Court and parliament. Otherwise the streets of the capital appeared calm.
Local newspapers and opposition leaders - including key Musharraf rival Benazir Bhutto, the former prime minister who returned last month from eight years in exile - accused the general of imposing martial law without announcing it.
But his government denied this. Attorney General Malik Mohammed Qayyum noted that the prime minister and parliament were still in place.
"There is no martial law in the country. Only a state of emergency has been declared," Qayyum said. "The civilian government will continue to function."
The U.S. called for Musharraf to restore democracy. However, the Pentagon said the emergency declaration does not affect U.S. military support for Pakistan and its efforts in the war on terrorism. Britain said it was deeply concerned.
Musharraf's leadership is threatened by an increasingly defiant court, the reemergence of political rival and former prime minister Benazir Bhutto and an Islamic movement that has spread to Islamabad. He said Pakistan was at a "dangerous" juncture and extremists had directly challenged the government's authority.
"The extremism has even spread to Islamabad, and the extremists are taking the writ of the government in their own hands, and even worse they are imposing their obsolete ideas on moderates," the president said in an address to the nation late Saturday on state-run television.
"Inaction at this moment is suicide to Pakistan and I cannot allow this country to commit suicide," he said.
Musharraf replaced the chief justice of the Supreme Court - who had emerged as the main check on his power - before a crucial Supreme Court ruling on his future as president. His emergency order accused some judges of "working at cross purposes with the executive" and "weakening the government's resolve" to fight terrorism.
He criticized the Supreme Court for failing to make a ruling yet on whether to validate his contentious victory in a presidential election, and for punishing government officers, including police. He said this had left the government system "semi-paralyzed."
Seven of the 17 Supreme Court judges immediately rejected the emergency, which suspended the current constitution. Police blocked entry to the Supreme Court building and later took the deposed chief justice and other judges away in a convoy, witnesses said.
In his television address, Musharraf said he hoped democracy would be restored following parliamentary elections.
"But, in my eyes, I say with sorrow that some elements are creating hurdles in the way of democracy," said Musharraf, who was wearing civilian clothes and spoke firmly and calmly. "I think this chaos is being created for personal interests and to harm Pakistan."
Speaking in English, Musharraf said he wanted to explain his actions to the United States and the West, reports Phillips.
"Please also do not demand your level of human rights, civil rights, civil liberties which you learned over the centuries. We are trying to learn and we are doing very well also, please give us time," he said.
Musharraf even quoted from Abraham Lincoln, citing a letter Lincoln had written suspending some constitutional provisions during the Civil War, adds Phillips. What Musharraf did not do, however, is say whether the elections planned for next year will actually happen.
The emergency comes as Musharraf's security forces struggle to contain pro-Taliban and al-Qaida-linked militants who have gained control of large tracts of the volatile northwest, near Afghanistan.
Violence has reached major cities with deadly suicide attacks in Islamabad and Karachi underscoring the failure of Musharraf's administration to combat the threat, despite huge financial support from the United States.
Talat Masood, a retired Pakistani general and respected analyst, said the emergency declaration was a pre-emptive move in case the court ruled against him, and said the move could "further aggravate terrorism and extremism in the country and slide the country into anarchism."
Rick Barton, a Pakistan expert at the Washington-based Center for International and Strategic Studies, said Musharraf's move Saturday was like throwing a "wet blanket" on the problem.
"He's obviously not very popular, and it's not going to increase his popularity," Barton said. "Unless he develops a new line or is able to be more effective with his old line, he seems to be just buying time, an inevitable delay to his demise."
The order drew swift complaints from the United States and Britain - Musharraf's main Western allies. Secretary of State Condoleezza Rice urged restraint on all sides and a return to democracy.
The United States "does not support extraconstitutional measures," Rice said from Turkey, where she was participating in a conference with Iraq's neighbors.
Musharraf claimed that 61 terrorists have been freed on order from the court - an apparent reference a case that has been led by the now-deposed chief justice to press authorities over suspects held by intelligence agencies without charge.
"Extremists are openly roaming," he said "And no one knows whether any of the these freed men were behind recent bomb attacks."
Bhutto, a longtime rival of Musharraf who recently returned from eight years of exile, flew back to Pakistan from Dubai where she was visiting family. She left the airport under police escort and about 100 police and paramilitary troops were deployed outside her house, apparently as a protective cordon, witnesses said. A bomb disposal squad also searched the house before she arrived.
After her arrival at Karachi's Airport, Bhutto said she did not believe there would be fair elections as long as emergency rule remained in place.
"Unless General Musharraf reverses the course it will be very difficult to have fair elections," she told Sky News television by telephone. "I agree with him that we are facing a political crisis, but I believe the problem is dictatorship, I don't believe the solution is dictatorship.
"The extremists need a dictatorship, and dictatorship needs extremists."
The government halted all television transmissions in major cities other than state-controlled Pakistan TV. Telephone service in the capital, Islamabad, was cut.
Musharraf said some independent TV channels had contributed to the uncertainty in the country.
In justification, the emergency order obtained by The Associated Press said "the constitution provides no solution for this situation, there is no way out except through emergent and extraordinary measures," it said.
Musharraf, who seized power in a 1999 coup and has been a close ally of the United States since the Sept. 11, 2001, attacks, has struggled to contain spreading Islamic militancy that has centered along the Afghan border and spread to the capital and beyond. Hundreds have died in recent weeks.
Pakistanis have increasingly turned against the government of Musharraf, who failed earlier this year to oust Iftikhar Mohammed Chaudhry - the chief justice replaced Saturday.
It was not clear whether U.S. officials had advance knowledge of Saturday's action.
Rice said that to her knowledge, U.S. officials had yet to hear directly from Musharraf after his declaration. She said she last spoke with Musharraf a couple days ago but that other U.S. officials had made the American position clear to him more recently.
Rice would not detail the conversations, but did say the U.S. told Pakistani leaders that "even if something happens, that we would expect the democratic election to take place because Pakistan has got to return to a constitutional order as soon as possible, and Pakistanis have to have a prospect of free and fair elections."
Crucial parliamentary elections meant to restore civilian rule are due by January. Musharraf himself was overwhelmingly re-elected last month by the current parliament, dominated by his ruling party, but the vote was challenged.
The Supreme Court has emerged this year as the main check on Musharraf's dominance and is due to issue a verdict on whether he could run for president while still serving as army chief before his current term expires Nov. 15.
Analysts said Musharraf was on shaky legal ground in his re-election by lawmakers last month - a vote that was boycotted by most of the opposition - but they still expected the court to rule in his favor to prevent further destabilizing Pakistan.
However in recent days, some judges had made comments that they would not be swayed by threats from senior officials that an emergency might be declared if the court ruled against the general.
The seven Supreme Court judges rejected the declaration of emergency and ordered top officials, including the prime minister, and military officers not to comply with it. The two-page ruling said there were no grounds for an emergency "particularly for the reasons being published in the newspapers that a high profile case is pending and is not likely to be decided in favor of the government."
At least seven trucks brought armed police and paramilitary ranger troops to Constitution Avenue that passes in front of the court, Parliament and the official residences of the president and prime minister.
Paramilitary troops behind rolled barbed wire blocked access to an official compound housing lawmakers - barring even wives, children and even a ruling party senator from entering.
Bhutto, seen by many supporters as key to a possible return to democracy, went to Dubai after being targeted by assassins in Pakistan last month. Suicide bombers attacked her homecoming parade after eight years in exile, killing more than 140 people.
Musharraf's order allows courts to function but suspends some fundamental rights guaranteed by the constitution, including freedom of speech. It also allows authorities to detain people without informing them of the charges.
The emergency was expected to be followed by arrests of lawyers and other perceived opponents of the government, including civil society activists and possibly even members of the judiciary itself, a ruling party lawmaker said on condition of anonymity because of the sensitivity of the issue.
By early Sunday, cell phone service appeared to have been restored, but landlines were still dead. Transmissions by TV networks remained off the air in major cities other than state-controlled Pakistan TV.
Musharraf said some independent TV channels had contributed to the uncertainty in the country.
He also issued two ordinances toughening media laws, including a ban on live television broadcasts of "incidents of violence and conflict." Also, TV operators who "ridicule" the president, armed forces, or executive, legislative or judicial organs of the state can be punished with three years in jail.
Nawaz Sharif, a former prime minister who was deported in September as he tried to return from exile, condemned the emergency and said Musharraf should resign. He urged Pakistanis to rise against Musharraf.