US prosecutors charged a Pakistani-American on Tuesday with attempting to blow up a car bomb in New York's busy Times Square while officials in Pakistan arrested several of his relatives.
Faisal Shahzad, a naturalized US citizen born in the Kashmir region of Pakistan, admitted to receiving bomb-making training in his country, according to charges filed by prosecutors.
"After the arrest Shahzad admitted that he had attempted to detonate a bomb in Times Square. He also admitted that he had recently received bomb-making training in Waziristan, Pakistan," the charges said.
He also told authorities he acted alone in Saturday's failed bombing but skeptical investigators are looking into his recent trip to Pakistan, a US law enforcement source said.
Shahzad, 30, was arrested late on Monday night after he was taken off an Emirates airline plane that was about to depart for Dubai. Hours later, several relatives and a friend were arrested in Pakistan in connection with the failed bombing, a security official in Karachi said.
Shahzad is from the disputed Kashmiri region but it was not known if he was affiliated with any militant group, a source familiar with the investigation said. The source asked not to be named because the issue is sensitive.
"Which group he may have belonged to and how he became radicalized, we don't know yet," said the source.
An intelligence official in Pakistan said Shahzad received militant training in northwest Pakistan near the garrison town of Kohat. The area around Kohat is a stronghold of Tariq Afridi, the main Pakistani Taliban commander in the region.
But the weapon he is accused of trying to detonate was crude: a collection of metal fuel tanks and plastic gasoline containers combined with non-explosive fertilizer and alarm clocks.
Although markets shrugged off the New York car bomb attempt as a one-off situation, tensions are high among investors. News that police in London closed a subway station to investigate reports of a suspect package pushed US stock index futures to session lows before the market opened on Tuesday.
Shahzad was due to appear in federal court later on Tuesday or Wednesday to face the terrorism-related charges, which carry a life sentence if he is convicted. Had the bomb detonated, many people could have died, experts said.
"He's admitted to buying the truck, putting the devices together, putting them in the truck, leaving the truck there and leaving the scene," the law enforcement source told Reuters, speaking on condition of anonymity. "He's claimed to have acted alone.
"Based on our collective experience it's hard to really believe that this is something someone would do on their own. It seems hard to pull off alone. There's a lot we don't know yet," the source said.
(Additional reporting by Michelle Nichols in New York; Jeremy Pelofsky and Jim Vicini in Washington; and William Maclean in London; Editing by Anthony Boadle)