Terror Plot Foiled In London

Cops Say Terrorists Were Planning To Blow Up Planes Flying To U.S.

(CBS/AP)  Police in London say they have thwarted a major terrorist plot intended to blow up planes, reportedly over the Atlantic while flying to the U.S. Twenty-one suspects are in custody, after a series of arrests overnight.

U.S. counterterrorism officials say United, American and Continental Airlines were targets of the plot, described by a top British police official as "intended to be mass murder on an unimaginable scale."

CBS News Correspondent Bob Orr says officials will not comment on who, or what group, is behind the plot. One official told CBS News: "We know of no immediate threat to US domestic flights. But, we are taking this very seriously. We view the plot as serious and substantial."

Deputy Commissioner Paul Stephenson says the arrests were in London, its suburbs and in Birmingham, and that searches continue in a number of locations.

Britain's Home Secretary, John Reid, says about a dozen of the the suspects were "very close" to succeeding in the plot, which he describes as "significant" and designed to cause loss of life.

Reid also says the plot was uncovered and foiled by British police who have been conducting an undercover operation for a number of months.

Sky News reports the plot may have involved blowing up 20 planes in mid-air over the Atlantic Ocean.

A British police official, commenting anonymously because of the sensitivity of the case, says the plotters planned for a number of planes to blow up at the same time, while in mid-air on the way to the U.S.

He says the suspects are "homegrown," though it was not immediately clear if all of the people in custody are British citizens. The official says police investigating the foiled attack are working closely with the South Asian community.

Multiple airlines with flights to multiple U.S. airports were at risk, according to a western counterterrorism official. Another official refused to identify the airlines because they were still being notified of the threat but referred to them as the "usual suspects." In the past, U.S. cities with terrorism threats or plots have included Washington, New York, Boston and Los Angeles. Airlines whose planes were hijacked on Sept. 11, 2001, were United Airlines and American Airlines. British Airways has also dealt with numerous threats in recent years.

A U.S. law enforcement official said there have been no arrests in the United States connected to the plot.

A senior U.S. counterterrorism official said authorities believe dozens of people - possibly as many as 50 - were involved in the overseas plot. The plan "had a footprint to al Qaeda back to it," said the official, speaking on condition of anonymity because of the sensitivity of the situation.

The plan involved airline passengers hiding explosives in carryon luggage, the official said. "They were not yet sitting on an airplane," but were very close to traveling, the official said, calling that the plot was "the real deal."

Another Western counterterrorism official, also speaking on condition of anonymity about the highly sensitive investigation, called the investigation "very serious."

"This is the real deal," the official said, adding that the reason "they have taken the action they've done is because you don't know what you don't know."