Plan failed after Tsarnaev brothers found hijacked car was low on gas

The Boston Marathon bombers were headed for New York's Times Square to blow up the rest of their explosives, authorities said, in what they portrayed as a chilling, spur-of-the-moment scheme that fell apart when the brothers realized the car they had hijacked was low on gas.

New York City Police Commissioner Raymond Kelly said Dzhokhar Tsarnaev told interrogators from his hospital bed that he and his older brother had decided spontaneously last week to drive to New York and launch an attack.

In their stolen vehicle, they had five pipe bombs and a pressure-cooker explosive like the ones that blew up at the marathon, Kelly said.

Mayor Michael Bloomberg said, "New York City was next on their list of targets."

The plan fell apart when the Tsarnaev brothers got into a shootout just outside Boston that left Tamerlan Tsarnaev dead, Kelly said.

Mayor Bloomberg said: "We don't know if we would have been able to stop the terrorists had they arrived here from Boston. We're just thankful that we didn't have to find out that answer."

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 if found guilty. He has been released from a civilian hospital and transferred to a federal medical detention center in central Massachusetts.

The US Marshals Service said on Friday that he left Beth Israel Deaconess Medical Center overnight and was taken to the Federal Medical Center in Devens about 65 km west of Boston.

Christina DiIorio-Sterling, a spokeswoman for US Attorney Carmen Ortiz in Boston, would not comment on whether authorities plan to add charges based on the alleged plan to attack New York.

The Middlesex County district attorney's office also is building a murder case against the surviving Tsarnaev for the death of Massachusetts Institute of Technology police officer Sean Collier three days after the bombings, office spokeswoman Stephanie Guyotte said.

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 US Attorney's office entered the room and advised him of his rights to keep quiet and seek a lawyer, according to a US law enforcement official and others briefed on the interrogation.

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."

In a show of force, police cruisers with blinking red lights were lined up in the middle of Times Square on Thursday afternoon, and uniformed officers stood shoulder to shoulder.

"Why are they standing like that? This is supposed to make me feel safer?" asked Elisabeth Bennecib, a tourist from Toulouse, France. "It makes me feel more anxious, like something bad is about to happen."