Updated 5:27 p.m. ET
BEIRUT - In a sharp escalation of Syria's crackdown on dissent, thousands of soldiers backed by tanks poured Monday into the city where the five-week-old uprising began, opening fire indiscriminately on civilians before dawn and killing at least 11 people, while 14 others lay in the streets - either dead or gravely wounded, witnesses said. Activists said the death toll could rise.
The offensive into the southern city of Daraa was planned in comprehensive detail: electricity, water and mobile phone services were cut. Knife-wielding security agents conducted house-to-house sweeps, neighborhoods were sectioned off and checkpoints set up suggesting Syria planned to impose military-style control on the city and other areas in the country.
"They have snipers firing on everybody who is moving," said a witness who spoke to The Associated Press by telephone, asking that his name not be used out of fear for his own safety.
"They aren't discriminating. There are snipers on the mosque. They are firing at everybody," he said.
Separately Monday, a White House spokesman said the U.S. is considering targeted sanctions against Syria in light of the violent crackdown.
Monday's statement from National Security Council spokesman Tommy Vietor was the first time officials had said publicly that sanctions were possible in Syria, where more than 300 people have been killed in an uprising against President Bashar Assad's regime.
The United States had issued increasingly forceful statements in recent days condemning the crackdown by Assad's government, but the violence has escalated anyway.
The offensive into Daraa was the most intense in a series of actions to put down dissent and appeared part of new strategy for pre-emptive strikes against the opposition to President Bashar Assad's regime rather than reacting to marches and protests.
The massive assault into Daraa appeared to be part of new strategy for crippling pre-emptive strikes against any opposition to President Bashar Assad, rather than reacting to marches and protests. Other crackdowns and sweeping arrests were reported on the outskirts of Damascus and the coastal town of Jableh bringing more international condemnation and threats of targeted sanctions by Washington.
But the assault on Daraa, an impoverished city on the Jordanian border, was by far the biggest in scope and firepower. Video shot by activists purported to show tanks rolling through streets and over fields. Youths pelted the passing tanks with stones and hospital hallways were later crowded with those injured, including one man whose jaw had been blow open by apparent gunfire, the video showed.
"Let Obama come and take Syria. Let Israel come and take Syria. Let the Jews come," shouted one Daraa resident over the phone. "Anything is better than Bashar Assad."
Razan Zeitounia, a human rights activist in Damascus, said the widespread arrests often of men along with their families appear to be an attempt to intimidate protesters and set an example for the rest of the country.
More than 350 people have been killed across the country since the uprising began in mid-March, touched off by the arrest of teenagers in Daraa who scrawled anti-government graffiti on a wall. But the relentless crackdowns have only emboldened protesters, who started with calls for modest reforms but are now increasingly demanding Assad's downfall.
"We need international intervention. We need countries to help us," shouted a witness in Daraa.
An eyewitness counted 11 corpses, with another 14 lying in the streets, apparently dead or gravely injured.
All witnesses spoke on condition of anonymity for fear of reprisals. Syria has banned nearly all foreign media and restricted access to trouble spots since the uprising began, making it nearly impossible to get independent assessments.
There were conflicting reports about whether Syria sealed the border with Jordan, although the head of Syria's Customs Department said crossings across the frontier were open as normal.
A Jordanian taxi driver said the border was open, but the main highway linking Syria with Jordan was blocked.
"The situation on the highway is scary," he said. "Protesters are burning tires and hurling stones at the army, which is responding with live fire, shooting randomly at civilians."
Assad has blamed most of the unrest on a "foreign conspiracy" and armed thugs, and has used state media to push his accusations.
On Monday, Syria's state-run television repeatedly ran lingering, gruesome closeups of dead soldiers, their eyes blown out and parts of their limbs missing, to back up their claims that they were under attack. The footage then flips to the soldiers' funeral marches, with men waving red, black and white Syrian flags and hoisting photos of Assad.
Syrian television also quoted a military source as saying army units, "answering the pleas for help by residents of Daraa" entered the city to bring security.
Unrest in Syria has repercussions well beyond the country's borders.
Syria has a pivotal role in most of the flashpoint issues of the Middle East from the Arab-Israeli peace process to Iran's widening influence because of its alliances with militant groups such as Lebanon's Hezbollah and Shiite powerhouse Iran.
Instability in Syria also throws into disarray the U.S. push for engagement with Damascus, part of Washington's plan to peel the country away from Hamas, Hezbollah and Tehran.
Syria already is subject to numerous penalties as it is deemed a "state sponsor of terrorism" by the State Department, but it maintains diplomatic relations with Washington.
Monday's sweep into Daraa, in a province of about 300,000 people, sought to hit the opposition movement at one of its pillars. The protests against Assad began there in March and several political figures from the area have stepped down to protest the violence in embarrassing defections from the regime.
The area was ripe for unrest: The grip of Syria's security forces is weaker on the border areas than around the capital, Damascus, and Daraa hasn't benefited from recent years of economic growth. Meanwhile, Daraa has absorbed many rural migrants who can no longer farm after years of drought.
In recent days, there had been signs that the regime was planning to launch a massive push against the opposition.
Last week, Assad fulfilled a key demand of the protest movement by abolishing nearly 50-year-old emergency laws that had given the regime a free hand to arrest people without cause. But he coupled the concession with a stern warning that protesters would no longer have an excuse to hold mass protests, and any further unrest would be considered "sabotage."
When protesters defied his order and held demonstrations Friday the main day for protests around the Arab world they were met with a gunfire, tear gas and stun guns.
In Geneva, the U.N. human rights chief, Navi Pillay, said Syria has turned its back on international calls to "stop killing its own people."
"Instead, the government's response has been erratic, with paper reforms followed by violent crackdowns on protesters ... The killings must stop immediately," Pillay said.
Still, the regime was clearly stepping up its efforts to crush the uprising, which has posed the gravest challenge to the 40-year ruling dynasty by Assad and his father, Hafez, before him.
The violence also has showed signs of exacerbating sectarian tensions within Syria.
The country has multiple sectarian divisions, largely kept in check under Assad's iron rule and secular ideology. The majority of the population is Sunni Muslim, but Assad and the ruling elite belong to the minority Alawite sect, an offshoot of Islam's Shiite branch that dominates in Iran, Iraq and Bahrain.