As investigators continued to search the homes of suspects connected with a plot to explode U.S.-bound jetliners, officials tell CBS News the most critical evidence was discovered about 10 days ago when British intelligence agents secretly broke into one residence and found the bomb-making material — both the liquid ingredients and the detonators.
Officials are trying to keep details about the bombs secret in order to prevent other terrorists from copying the design, reports CBS News national defense correspondent David Martin.
But the director for Homeland Security made it clear Friday that these devices have never been seen before.
"We're going to reengineer what they've done. We're going to see how that differs from things we've known about and how it's the same," Michael Chertoff said.
The so-called "sneak and peek" job that uncovered the bombs was the beginning of the end game for an investigation that began with a tip from a member of Britain's Muslim community in the wake of last summer's subway bombings.
One of the suspected plotters was tracked to Pakistan, where he apparently met with a man named Rashid Rauf, who both U.S. and Pakistani officials say has links to al Qaeda, Martin reports.
Rauf allegedly directed the bomb plot from Pakistan and sent at least one message urging the plotters in London to push ahead more quickly.
Officials say they don't know whether Rauf was the ring leader or simply a go-between who relayed instructions from senior al Qaeda operatives.
Also Friday, British authoritiesin connection the alleged plot and froze their assets, while investigators probed their movements, backgrounds and finances.
Many of the names released by the Bank of England, acting on an order from the government, were of Muslim origin, many of which are common in Pakistan. The suspects ranged in age from 17 to 35.
Authorities said Thursday the plot would have caused "mass murder on an unimaginable scale." At least one of the 24 people arrested was reportedly a woman with a small child; another was a convert to Islam.
The Metropolitan Police said late Friday that one of the 24 people was released without being charged.
Police did not identify the person who was released, nor did they say if the person remained a suspect. Twenty-two of the others had their detentions extended through to Wednesday. The final person's detention hearing was delayed until Monday, but the suspect remained in custody.
In Pakistan, authorities arrested five people, bringing the total number of suspects held there to seven. A Pakistani official said the five Pakistanis were believed to have been helping two British citizens who were taken into custody there a week ago.
Investigators, describing a plot on the scale of the Sept. 11 attacks in the United States, said the attackers planned to use common electronic devices to detonate liquid explosives to bring down as many as 10 planes.
The bombs were to have been assembled on the aircraft apparently with peroxide-based solution and everyday carry-on items such as a disposable camera or a music player, two U.S. law enforcement officials told The Associated Press on Thursday. The officials spoke on condition of anonymity because Britain asked that no information be released.
A U.S. law enforcement official in Washington said that at least one martyrdom tape was found during ongoing raids across England.
Also Friday,in a security crackdown after the thwarting of the British airline plot, the Interior Ministry said, without elaborating.
The Guardian newspaper, citing unidentified British government sources, said that after the first two arrests were made in Pakistan, a message was sent to Britain telling the plotters, "do your attacks now."
That message was intercepted and decoded earlier this week, The Guardian said.
Authorities pressed ahead with efforts to smash the purported terror ring. Two U.S. officials said British, U.S. and Pakistani investigators were trying to trace the steps of the suspects in Pakistan and were seeking to determine whether a couple of them attended terrorist training camps there.
Many of the suspects were said to be British Muslims and neighbors said at least two were converts to Islam.
Raids were carried out at homes in London, the nearby town of High Wycombe and in Birmingham in central England. Police still guarded homes in High Wycombe, where the Muslim community expressed shock and anger at being thrust into the international spotlight.
"They are considered ordinary British Muslims and they haven't caused any harm to anyone," accountant Mohammed Naeem said of those arrested. "They come from decent families."
Naeem said that the Muslim community supports efforts to promote security, but that the police have acted on faulty intelligence in the past. He cited a recent raid in London in which police were forced to apologize for shooting an innocent Muslim man.
Imtiaz Qadir, of the Waltham Forest Islamic Association, said one of the suspects was a woman in her 20s who had a 6-month old child. "They have taken the child too, because it needs to be with its mother," he said.
Neighbors identified another suspect as Don Stewart-Whyte, 21, from High Wycombe, a convert who changed his name to Abdul Waheed. Ibrahim Savant, of Walthamstow, one of the names on the Bank of England list, was a convert formerly known as Oliver, neighbors said.
CBS News reported that one of those arrested worked at Heathrow Airport.
A British police official, speaking on condition of anonymity because of the sensitivity of the investigation, said the suspects were "homegrown," though it was not immediately clear if all were British citizens.
British security officials estimate there are 1,200 radical Muslim operatives in the country, reports CBS News correspondent Sheila MacVicar.
Tariq Azim Khan, Pakistan's minister of state for information, said: "These people were born and brought up in the United Kingdom. Some of them may have parents who were immigrants from Pakistan."
Police would not say where the suspects were being held — which is not unusual in highly sensitive cases — but terrorist suspects are usually brought to the high-security Paddington Green police station, in central London.
British law permits terrorist suspects to be interrogated for up to 28 days without being charged, though after the first 48 hours court permission is required for further detention.
Airline passengers faced a second day of disruptions and disappointment Friday as airports struggled to restore flight schedules.
"It is going to be another difficult day today, both for airports and for passengers, but there is cause for optimism that we will get more flights off today," said Stephen Nelson, chief executive of the authority that runs Britain's major airports.
At Heathrow, Europe's busiest airport,, but many passengers turned around and headed home after an early morning announcement that a raft of flights had been canceled, including British Airways services to San Francisco and Los Angeles.
On Thursday, the U.S. issued its highest terrorism alert ever for commercial flights from Britain to the United States and raised the threat level to the next highest level for all domestic and international flights.
Counterterrorism officials said the targets were United, American and Continental Airlines flights from Britain to major U.S. destinations, probably including New York, Los Angeles and Washington.