London was in a state of lockdown Friday after police located the first device in the tourist epicenter of the city, and began a search of the city's tourist landmarks for others. Hours later, they found one, near Hyde Park.
CBS News correspondent Richard Roth reports the second car had originally been parked around the corner from the nightclub — it had been ticketed and towed overnight, a mile and a half away, to Park Lane, where the smell of gas fumes raised suspicion. It's clearly linked, police said, to the first car bomb.
British anti-terror police chief Peter Clarke said the bomb discovered in London's West End could have caused "significant injury or loss of life" had it exploded.
"The [second] vehicle was found to contain very similar materials to those that had been found in the first car," Clarke said. "There was a considerable amount of fuel and gas canisters. As in the first vehicle, there was also a quantity of nails. This, like the first device, was potentially viable."
However, sources have told CBS News that it is still too early to know if the plot is connected to al Qaeda or is limited to homegrown U.K. terrorists. Sources said the bombs found were not "amateurish."
Britain's new home secretary, Jacqui Smith, summoned top officials for an emergency meeting Friday, calling the attempted attack "international terrorism."
Hours later, police closed a major road on the edge of Hyde Park, and began clearing people out of the area following reports of a suspicious vehicle.
Deputy Metropolitan Police Commissioner Tarique Ghaffur said "our overriding objective is to protect, put in place cordons, and make sure areas are properly searched."
CBSNews.com's Tucker Reals reports on posts in Internet forums made the night before.
He said police were "reviewing plans" for events scheduled in London during the weekend.
"We are currently facing the most serious and sustained threat to our security from international terrorism," Smith told reporters after the emergency meeting. "This reinforces the need for the public to remain vigilant to the threat we face at all times."
Clarke said the car bomb was discovered after an ambulance crew was called to a nearby nightclub at about 1 a.m. because someone had taken ill inside. The crew noticed the car parked outside the Tiger Tiger Club and what appeared to be smoke inside the passenger area.
Police were called and explosives officers dismantled the device by hand.
"All I kept thinking was, thank God, there must be an angel on my shoulders," one woman said, "because if that had gone off — glass, everything — we wouldn't have been alive today.
Clarke commended the bravery of the bomb squad and said they had not only prevented possible damage and injury, but provided investigators with valuable evidence.
The BBC reported that almost 16 gallons of gasoline were found in the car, and that law enforcement sources said it was possible the device had failed to detonate before it was discovered.
Sky reported that police believed the device was to be detonated remotely by cell phone, and that an explosives officer who arrived early on the scene reached into the car and removed a phone that was part of the trigger system.
The central area of London where the device was found would have been packed with nightclub patrons at that hour of the night. Clarke said it was too early to tell whether the Tiger Tiger nightclub, outside of which the car was found, was the intended target of the plot.
"Forensic staff are still examining the device, but once we know more about it, we'll know more about what type of individuals are behind this," an official, who spoke on condition of anonymity because of the sensitivity of the security details, told the Associated Press earlier.
The incident also presented the first crisis for the cabinet of new Prime Minister Gordon Brown, reported Roth.
Brown, who took office on Wednesday, said the incident was a reminder that Britain faces "a serious and continuous threat" and the "need to be alert."
"I will stress to the Cabinet that the vigilance must be maintained over the next few days," Brown said.
Prof. Michael Clarke of King's College, a British terrorism analyst, told CBS News that the device appeared to be part of an "amateur" plot using a homemade bomb — but a large one. He said the device appeared to be part of a "well-coordinated" plan.
Peter Clarke told reporters that it was "too early to speculate as to who might be responsible... we are keeping an entirely open mind." He said a full investigation had been launched.
A BBC report cited anonymous officials in the government as saying initial signs pointed to an "international element" in the plot.
Intelligence sources who spoke to CBS News Friday morning seemed to express surprise at the discovery of the device, suggesting there had been "no warning, no intel, no smell" as a prelude to the plot — which reportedly had the British domestic intelligence agency, MI5, "very, very worried."
At his news conference Friday, Peter Clarke said there was "no indication that we were going to be attacked this way."
Prof. Clarke said that if the device was part of plot by a major Islamic terror group, there could well have been more devices planted in the city.
Aside from urging the public to remain vigilant, British authorities had not given any specific warning about other suspicious devices in the capital city.
This city — like most of this country — is blanketed by closed-circuit TV. Authorities now are poring over video for clues to help track down whoever left the bomb here.
Security video helped track the movements of suicide bombers almost exactly two years ago, but not until after their attack on London's transit system which killed fifty-two people.
Now Britain's camera network is being used to try and find a bomber — or bombers — to prevent another attack.
"London at 2 o'clock in the morning is full of surveillance cameras," Prof. Clarke said. "This person will have been caught on camera at least 200 times coming in from any of the suburbs into the center of the city."
"It's impossible to make a bomb without leaving plenty of DNA behind, so more will come from that, too," he said.
CBS News correspondent Mark Knoller reports that White House spokesman Gordon Johndroe said: "We commend the British security services for their action today. U.S. officials are in contact with their U.K. counterparts and will continue to monitor the situation."
Former Scotland Yard detective John O'Connor told CBS' Early Show that terror activities in Britain usually involve fairly well-orchestrated networks, with strategists "behind the scenes who choose the targets, who advise on the construction of the bombs."
He said these planners "normally get some dupe, some guy they've convinced should become a martyr for Islam ... to deliver the bomb."
O'Connor drew comparisons to the device found in London and others that are frequently used by terror groups in hot spots around the world, such as the Gaza Strip and Iraq.
"It's the people that are behind it that matter," he said.
The incident comes a week before the second anniversary of the July 7 London bombings, when four British Muslim suicide bombers killed themselves and 52 bus and subway passengers.
For more than a year, the government has held the country's terrorist threat level at severe — which means a terrorist attack is highly likely.
The Haymarket, where the car was found, is the site of restaurants, bars, a cinema complex and, most famously, theaters. On a Thursday night, the area would have been buzzing with crowds of people. The broad street links Piccadilly Circus in the north to the Pall Mall at its southern end.