According to CNN:
LONDON, England (CNN) -- As authorities were investigating an explosives-packed car discovered outside a nightclub near Piccadilly Circus on Friday, a second vehicle was found in London that had similar explosive material inside, security sources said.
The second car had been parked underground near Trafalgar Square in an area where parking was not allowed.
Workers towed it to a lot on Park Lane near Buckingham Palace and thought it smelled of gasoline. Given the reports that gas canisters were among the explosive material found in the other car, they became suspicious, security sources said.
Authorities then blocked off a section of Park Lane while they examined the car and discovered the material.
The sources did not say exactly what was found in the second car, but a U.S. source with knowledge of Britain's investigation said the second vehicle is linked to the first.
Earlier Friday, a section of Fleet Street also was cordoned off briefly, then reopened without incident.
Inside the first car near Piccadilly Circus, a device was found to be loaded with fuel, gas cylinders and nails, said security sources, and it was set up for remote detonation. (Watch police describe potential blast Video)
Security sources said that the "relatively crude device" contained at least 200 liters, or about 50 gallons, of fuel in canisters.
Police said the car was found shortly before 2 a.m. Friday and deactivated. The device could have caused huge numbers of casualties, police said.
British police anti-terror chief Peter Clarke said detectives were examining security camera footage for clues to the driver of the vehicle.
The incident renewed fears of a terrorist strike almost two years after London's transport network was hit by suicide bombers.
Security sources with knowledge of the investigation said a cell phone was found as part of the device, but it was not immediately clear whether it was to be used as a detonator or timer, or in some other way. The sources said the device was apparently set up for remote detonation.
Clarke said the car was first discovered when a quick-thinking ambulance crew noticed it was filled with smoke outside the popular Tiger Tiger nightclub.
Explosives officers discovered the fuel and nails attached to a "potential means of detonation" inside the vehicle. Officers "courageously" disabled the trigger by hand, Clarke said.
"Even at this stage it is obvious that if the device had detonated, there could have been severe injuries and loss of life," Clarke said. He said it was too early to say who was responsible.
Witness Daniel Weir said he was walking home from work when he noticed police had cordoned off the area around the nightclub and a nearby vehicle.
He snapped several photos, including one that showed a canister labeled "patio gas." (See the photos)
"If I known what was actually ... going on, I don't think I would have been hanging about," he told CNN hours later.
British Prime Minister Gordon Brown, appointed two days earlier in a transition of power seen as a potential spur for extremists to mount an attack, said the incident was a reminder of the dangers facing the country. (Full story)
Brown, whose predecessor's support of the Iraq war provoked anger among Islamic militants, said Britain faced "a serious and continuous threat" and the public needs to be alert at all times.
The incident came a little more than a week before the second anniversary of July 7, 2005, when four Islamic extremist suicide bombers killed 52 people and injured hundreds more on London's transport system in the deadliest strike on the city since World War II.