London in Horror......

LONDON, England (CNN) -- A manhunt is under way in London for the driver of a car abandoned in the center of the city that police say was packed with explosives that could have caused huge numbers of casualties.

Security sources told CNN's Paula Newton they believed the device -- loaded with fuel, gas cylinders and nails -- was intended to be detonated by cellphone.

British police anti-terror chief Peter Clarke said detectives were examining CCTV footage after the car was found outside a nightclub in the heart of London's busy theater district shortly before 2 a.m. (0100 GMT) on Friday.

Police deactivated the explosives but the incident stoked renewed fears of a terrorist strike almost two years after London's transport network was hit by deadly suicide bombers.

Hours later, another road in central London was closed as police investigated a "suspicious" vehicle. Park Lane, an upmarket address close to Buckingham Palace and the main Oxford Street shopping area was cordoned off.

Security sources told CNN that the "relatively crude device" found in the first car near Piccadilly Circus contained at least 200 liters, or about 50 gallons, of fuel in canisters.

LONDON - Police in London’s bustling nightclub and theater district on Friday defused a bomb that could have killed hundreds, after an ambulance crew spotted smoke coming from a Mercedes filled with a lethal mix of gasoline, propane and nails, authorities said.

The bomb near Piccadilly Circus was powerful enough to have caused “significant injury or loss of life” — possibly killing hundreds, British anti-terror police chief Peter Clarke said.

Authorities believe the bombers had intended to set the bomb off remotely, by cell phone, Sky News television reported, citing sources.

Britain’s new home secretary, Jacqui Smith, called an emergency meeting of top officials and later called the attempted attack “international terrorism.”

Hours later, police closed a major road, Park Lane, on the edge of Hyde Park after reports of a suspicious vehicle.

Sky News reported that the second vehicle was connected to the car bomb found earlier. But, prior to the television report, a police spokesperson said there was nothing to immediately suggest it was linked to the earlier incident.

CCTV key to investigation
Police planned to examine footage from closed-circuit TV cameras in the area, Clarke said, hoping the surveillance network that extends throughout the city would help track the driver.

Officers were called to The Haymarket, near Piccadilly Circus, after an ambulance crew — responding to a call just before 1:30 a.m. about an injury at a nearby nightclub — noticed the smoke, Clarke said.