A man who admitted plotting to bomb the city's subway system wanted to do so with the help of at least two other bombers during rush hour, when the most people could be killed, police said Tuesday.

"This was particularly disturbing," police Commissioner Raymond Kelly said. "It was his intention to be on trains during rush hour period and to kill New Yorkers. No question about it."

The man, 25-year-old Najibullah Zazi, pleaded guilty Monday to charges including conspiracy to use weapons of mass destruction and supporting Al Qaeda, which he said trained him in Pakistan.

The jailed Zazi has been cooperating with investigators since offering information about the bomb plot earlier this month, a law enforcement official has said. He faces life in prison without parole when he's sentenced in June, though his cooperation with authorities could earn him leniency.

A law enforcement official familiar with the Zazi investigation told The Associated Press that authorities were most interested in learning about Zazi's time in Pakistan and when Al Qaeda recruited him. The official said authorities also wanted information about the leadership and structure of the group that recruited him, Al Qaeda's tactics and names of any contacts.

Authorities weren't searching for other suspects in the bomb plot, said the official, who spoke on the condition of anonymity because the case is ongoing.

Kelly promised more details about the plot would emerge as others charged proceeded through the courts. He said law enforcement officials were confident they had identified the plot's participants.

"It is a very significant case," he said. "This was the real deal."

Kelly's remarks echoed those of U.S. Attorney General Eric Holder, who said on Monday in Washington that the planned bombings "could have been devastating."

On Monday, Zazi, a former Colorado airport shuttle driver, told a judge he traveled to New York last September with explosive materials he planned to use to assemble bombs to attack city subways after the Sept. 11 anniversary. He was arrested before he could carry out the suicide mission.

During his plea in Brooklyn federal court, Zazi admitted using notes taken at an Al Qaeda training camp in Waziristan, Pakistan, to build homemade explosives with beauty supplies purchased in the Denver suburbs and cooked up in a Colorado hotel room. He said he dumped the explosive material when he realized he was being trailed by law enforcement.

Zazi said he originally went to join the Taliban and fight the U.S. military in Afghanistan, his native land, because of civilian deaths there but Al Qaeda recruited him for the subway bombing plot.

Others charged in the case include Zazi's uncle and father and two of Zazi's friends, Zarein Ahmedzay and Adis Medunjanin, who traveled to Pakistan with him in 2008.

Medunjanin has pleaded not guilty to charges he conspired to kill U.S. soldiers in Afghanistan. His lawyer, Robert C. Gottlieb, said Tuesday he didn't know if Zazi told prosecutors anything about his client but Zazi's decision to plead guilty "obviously affects the overall prosecution."

Ahmedzay has pleaded not guilty to charges that he lied to the FBI during the probe about places he visited during the 2008 trip.

Zazi's father was accused this month of trying to get rid of chemicals and other evidence. Prosecutors, after initially demanding that he be jailed in Brooklyn without bail, agreed to a deal on Feb. 17 releasing him on $50,000 bond and allowing him to return to his home in suburban Denver.

Attorney Ron Kuby, who represents Ahmad Wais Afzali, an imam authorities claim tipped off Zazi about the investigation, predicted Zazi's case would lead to more pleas.

"As a general rule in these cases, once the alleged mastermind takes the plea, the miniminds sign on as well," he said.

Fordham University School of Law Professor James Cohen said Zazi represents a cautionary tale. He said Zazi, like other Muslims, felt isolated and unhappy with the actions of the United States around the world and its perceived favoritism of Israel.

"They are feeling left out and are very angry about it," Cohen said. "That's what we have to come to grips with. An identifiable part of the Muslim population is willing to do just about anything in terms of suicide bombings. Believe it."