Updated at 7:10 p.m. ET
The suspects in deadly bombing at the Boston Marathon also planned to attack Times Square in New York, authorities announced Thursday.
"The surviving attacker revealed that New York City was next on their list of targets," New York Mayor Michael Bloomberg said during an afternoon news conference. "He told the FBI, apparently, that he and his brother had intended to drive to New York and designate additional explosives in Times Square."
Police Commissioner Raymond Kelly said Dzhokhar Tsarnaev told interrogators from his hospital bed that he and his older brother had decided spontaneously Thursday night to drive to New York and launch an attack with their five pipe bombs and a pressure-cooker bomb like the ones that blew up at the marathon.
Kelly said that the city was notified by the FBI's Joint Terrorism Task Force Wednesday night about the intentions of Tsarnaev and his older brother Tamerlan Tsarnaev.
Dzhokhar Tsarnaev traveled to New York at least once last fall. There is a photo of the suspect in Times Square.
The plan fell apart after the Tsarnaev brothers were intercepted by police in a stolen car and got into a fierce gun battle that left Tamerlan Tsarnaev dead, Kelly said.
"We don't know if we would have been able to stop the terrorists had they arrived here from Boston," Bloomberg said. "We're just thankful that we didn't have to find out that answer."
CBS News correspondent John Miller reported that from the moment the NYPD understood that the explosions at the Boston Marathon were the result of a bombing, they snapped into place a well-honed plan. It's called the CRV, critical vehicle response, and it involves flooding anything that could be the next possible target with an overwhelming show of force. That show of force was Times Square. It's part of a strategy to help prevent coordinated attacks at multiple locations.
As for what Commissioner Kelly meant by the brothers being spontaneous, Miller said that once they Were identified they knew things had to speed up. "So they went from being organized bombers to disorganized bombers," said Miller. "And I guess the irony here is if they had actually completed their drive to Times Square to place their bombs, what they would have run into wasa couple of hundred cops waiting for them."
Dzhokhar, 19, is charged with carrying out the Boston Marathon bombing that killed three people and wounded more than 260, and he could get the death penalty.
Kelly, citing interrogations carried out by the task force investigating the Boston Marathon attack, said that days after the bombing, the Tsarnaev brothers "planned to travel to Manhattan to detonate their remaining explosives in Times Square."
"They discussed this while driving around in a Mercedes SUV that they hijacked after they shot and killed the officer at MIT," the police commissioner said. "That plan, however, fell apart when they realized that the vehicle they hijacked was low on gas and ordered the driver to stop at a nearby gas station."
The driver escaped and called police, Kelly said. That set off the gunbattle and manhunt that ended a day later with Dzhokhar captured and 26-year-old Tamerlan dead.
Miller reported that the amount of fuel in the car's tank wasn't the major obstacle in the brothers' plan.
"It wasn't but for a tank of gas in the car," said Miller. "It was but for running into a bunch of cops with 200 machine guns."
On Tuesday, Miller reported on "CBS This Morning" that, according to investigators, the carjacking victim speaks little to no English, but authorities pressed him to remember recognizable words from his exchange with the bombing suspects.
The suspects openly boasted to the victim in English about their role in last week's bombing and carried out the rest of their exchange in Russian, Miller reported.
Miller reported that the victim said, "The only word I recognized was Manhattan," a word which "tripped a lot" of alarm for authorities, who quickly halted Amtrak service from Boston to New York and searched the trains.
The tip prompted the New York Police Department to "flip on its network of license plate readers at all bridges and tunnels coming into the city," Miller said. "They loaded all the license plates associated with these guys" to prevent possible entry into Manhattan.
On Wednesday, Kelly told reporters that he was told Dzhokhar Tsarnaev may have been intending to come to New York to party, or for a party, sometime after the bombings.
After his arrest, Dzhokhar was interrogated in his hospital room over a period of 16 hours without being read his constitutional rights. He immediately stopped talking after a magistrate judge and a representative from the U.S. attorney's office entered the room and gave him his Miranda warning, a U.S. law enforcement official and others briefed on the interrogation told The Associated Press.
Tamerlan had come under scrutiny from the FBI, the CIA and Russian intelligence well before the Boston attack. The CIA had added Tamerlan's name to a terrorist database 18 months ago, after Russian intelligence flagged him as a possible Muslim radical, a U.S. official told Miller Thursday.