Boston Marathon Bombings Update: Suspects planned Times Square attack, officials say

(CBS) - The accused Boston Marathon bombers were planning to drive to New York City and explode their remaining bombs in Times Square following the Boston attack, New York Police Commissioner Ray Kelly said at a press conference on Thursday. 

PICTURES: Boston bombing victimsPICTURES: Boston Marathon bombing suspects

Authorities learned of the plan after interrogating 19-year old Dzhokhar Tsarnaev, Kelly said. Dzhokhar and his brother Tamerlan Tsarnaev, who was killed in a shootout with police, decided on a New York attack "spontaneously" as they drove a hijacked Merdeces Benz SUV through Cambridge, Kelly said.

According to to Kelly, the plan "fell apart" when the brothers realized the SUV was out of gas. He said Tsarnaev told investigators that the owner of the car was able to escape after the two ordered him to pull over at a gas station.

"[Dzhokhar Tsarnaev]] initially told investigators he and his brother decided after the Boston bombing they would go to New York City to party," Kelly said. "However, subsequent questioning of Dzhokhar revealed he and his brother decided spontaneously on Times Square as a target."

Investigators believe that after the Boston bombings, the brothers had six remaining improvised explosive devices, Kelly said. One was a pressure cooker device similar to the bomb used in the Boston attack, and the remaining five were pipe bombs.

Dzhokhar Tsarnaev was photographed in New York City in April and November of 2012, Kelly said, and investigators are working to determine who he was with at the time of his visits.

Kelly and New York Mayor Michael Bloomberg said there are police resources including officers and cameras in Times Square, but it is unknown whether officials would have been able to stop an attack there.

"We have a lot of presence there, a lot of resources there, but there are no guarantees," Kelly said.

Complete coverage of Boston Marathon bombings on Crimesider