Glasgow police chief Willie Rae announced late Saturday that the incidents were connected, and Britain raised its security alert level to critical — the highest possible level indicating terror attacks may be imminent.
The two Mercedes found in London Friday had been loaded with gasoline, gas canisters and nails in one of the capital's busiest areas on a night when Londoners like to go out and party.
Police mounted increased patrols as detectives conducted an intense hunt for a man seen running from one of the cars in the heart of the city's entertainment district.
CBS News has learned the police have been able to reconstruct the journey of the bomb vehicles through London using closed-circuit TV images.
And, CBS News correspondent Sheila MacVicar reports, using license plate recognition technology, the police now know precisely where and when the bombers brought their cars into central London.
Those video cameras are sophisticated and sensitive at night. Sources say there are good quality images of both drivers. CBS News has learned that the police know the identity of at least one of the suspects.
The vehicles were found abandoned in the early hours of Friday in what police believe was an attempt to kill scores or even hundreds of people. Detectives said they were keeping an open mind about who the bombers were, but terrorism experts said the signs pointed to a cell linked to or inspired by al Qaeda.
One car was abandoned outside the Tiger Tiger nightclub on Haymarket, a busy street of shops, clubs, theaters and restaurants just a short walk from Trafalgar Square and Piccadilly Circus.
The other had been towed after being parked illegally on nearby Cockspur Street and was discovered in an impound lot about a mile away in Park Lane, near Hyde Park.
Deputy Assistant Commissioner Peter Clarke, the Metropolitan Police anti-terrorism chief, said the two devices could have caused "significant injury or loss of life."
"The discovery of what appears to be a second bomb is obviously troubling, and reinforces the need for the public to be alert," he said.
The plot rattled London a week before the second anniversary of the July 7 suicide bombings that killed 52 commuters on the city's transit system, and two days after Gordon Brown took office.
"London on the Edge" said the front page headline in The Independent newspaper on Saturday, while the Daily Mail asked, "Where's the Next Bomb?"
Mayor Ken Livingstone urged Londoners to remain vigilant.
"The discovery of two potential car bombs in central London, with those responsible still at large, means we face a very real threat of terrorist attack at this moment in time," he said.
The Times newspaper reported that police had distributed a document to nightclubs two weeks ago warning of the threat from "vehicle-borne explosive devices" — car bombs. The document, prepared by the National Counterterrorism Security Office, took the form of general counterterrorism advice for British clubs.
Terrorism experts said the improvised devices discovered Friday were similar to ones used by homegrown terror cells — much like the bombs used in the July 7 attacks — although the discovery of the second device suggested a coordinated and more sophisticated attack.
Intelligence officials were examining a post to an Islamist Web site —, as first reported by CBS News — that suggested Britain would be attacked for awarding a knighthood to the novelist Salman Rushdie and for intervening in Muslim countries.
CBS News found the posting, which went on for nearly 300 words, on the "al Hesbah" chat room. It was left by a person who goes by the name abu Osama al-Hazeen, who appears regularly on the forum. The comment was posted on the forum, according to time stamp, at 08:09 a.m. British time on June 28 – about 17 hours before the bomb was found early on June 29.
Al Hesbah is frequently used by international Sunni militant groups, including al Qaeda and the Taliban, to post propaganda videos and messages in their fight against the West.
There was no way for CBS News to independently confirm any connection between the posting made Thursday night and the car bomb found Friday.
Al-Hazeen's message begins: "In the name of God, the most compassionate, the most merciful. Is Britain Longing for al Qaeda's bombings?"
Al-Hazeen decries the recent knighthood of controversial author Salman Rushdie as a blow felt by all British Muslims. "This 'honoring' came at a crucial time, a time when the whole nation is reeling from the crusaders attacks on all Muslim lands," he said, in an apparent reference to the British role in Iraq.
"We say to Britain: The Emir of al Qaeda, Sheikh Osama, has once threatened you, and he carried out his threats. Today I say: Rejoice, by Allah, London shall be bombed," the message reads.
Speaking at a news conference Friday after the bomb scare in central London, the Metropolitan Police force's Counter-Terrorism Commander Peter Clarke said that officials had "no indication that we were going to be attacked this way".
Prior to the Thursday night posting by al-Hazeen, there had been no specific allusions to threats against London or Britain seen on al Hesbah, or any other major jihadist forums in recent weeks.