City officials say the alleged suspects behind the Boston Marathon bombings were also planning to attack New York.
Speaking to reporters at City Hall on Thursday, Mayor Michael Bloomberg and Police Commissioner Ray Kelly said Tamerlan Tsarnaev, 26, and Dzhokhar Tsarnaev, 19, had a pressure cooker bomb and five pipe bombs they wanted to set off in Times Square.
The Federal Bureau of Investigation says the younger brother spontaneously planned the New York attack in the days following the marathon bombings.
Officials say the decision came after the killing of MIT security officer Sean Collier and before the suspects had a shootout with police in Watertown, Mass. when Tamerlan Tsarnaev was killed.
"Dzhokhar Tsarnaev, the terror suspect who was captured alive, initially told investigators that he and his brother decided after the Boston bombings that they would go to New York City to 'party.' However, subsequent questioning of Dzhokhar revealed that he and his brother decided spontaneously on Times Square as a target," said Kelly.
According to the police commissioner, the vehicle they carjacked did not have enough gas to make it to New York so when they stopped at a service station, the carjacking victim was able to get away and contact police
In the shootout that followed the older brother was killed, the younger one captured hours later hiding in a boat.
The FBI did not comment on Thursday on the case's connection to New York.
Federal officials confirm they spent about 16 hours questioning the teen before he was read his Miranda rights, at which point he stopped talking.
City officials said they had to release information on this new development, as a serious reminder that New York remains a high target for terrorists.
"We have an obligation, we believe, to put that information out," the police commissioner said. "The information we received that he was a lot more lucid, and gave much more detailed information in the second questioning period."
"They had built these additional explosives, and we know that they had the capacity to carry out the attacks," the mayor said. "If god forbid they had arrived in New York City and gone to Times Square, one thing for sure, they would have seen an enormous police presence."
Kelly said Dzhokhar Tsarnaev was photographed in Times Square with friends on or around April 18, 2012, and returned to the city in November.
The commissioner says it is unknown if the visits were related in any way to the post-Boston terror plot.
Meanwhile, the father of the two suspects said he hopes to leave Russia soon for the United States.
His wife says she's not sure if she will go with him because she's worried about a shoplifting charge she faces here in the U.S. from last summer.
U.S. officials say Dzhokhar Tsarnaev acknowledged his role in the bombing and said his older brother recruited him for the attack.
He also said they were angry about the wars in Afghanistan and Iraq and the killing of Muslims.
The U.S. is also looking into whether it botched surveillance of Tamerlan Tsarnaev.
The CIA named him to a terrorist database 18 months ago after Russia raised concerns he had become radicalized.
The FBI had earlier investigated Tsarnaev and found no ties to organized terrorism groups.
He was killed during a gunfight with police on Friday.
Last week's bombings at the Boston Marathon left three people dead and more than 200 others wounded.