Small Explosion Rocks New York's Times Square

Sources tell ABC News that the device was made from a green ammunition can filled with explosive powder. It blew out the lower part of the glass -- it's being described as a "low explosive."

Witnesses staying at a Marriott hotel four blocks away told The Associated Press they heard, and felt the blast.

"I was up on the 44th floor and I could feel it. It was a big bang," Darla Peck, 25, of Portland, Ore., told the AP.

"It shook the building. I thought it could have been thunder, but I looked down and there was a massive plume of smoke so I knew it was an explosion," said Terry Leighton, 48, of London, who was staying on the 21st floor of the Marriot.