"They can give me a cavity search right now and I'd be perfectly happy," said Daniel Wood, a video producer from New York City who was waiting for a train.
Similar pressure-cooker explosives have been used in Afghanistan, India, Nepal and Pakistan, according to a July 2010 joint FBI and Homeland Security intelligence report. Also, one of the three devices used in the May 2010 Times Square attempted bombing was a pressure cooker, the intelligence report said.
"Placed carefully, such devices provide little or no indication of an impending attack," the report said.
The Pakistani Taliban, which claimed responsibility for the 2010 attempt in Times Square, has denied any role in the Boston Marathon attack.
The two bombs blew up about 10 seconds and around 100 yards apart yesterday near the finish line of the storied, 26.2-mile race, tearing off limbs, knocking people off their feet and leaving the streets spattered with blood and strewn with broken glass. The dead included an 8-year-old boy. An Amesbury woman is among the injured.
Richard Barrett, the former U.N. coordinator for an al-Qaida and Taliban monitoring team who has also worked for British intelligence, said the relatively small size of the devices in Boston and the timing of the blasts suggest a domestic attack rather than an al-Qaida-inspired one.