Investigators say a witness saw two teenagers flee the scene after a makeshift explosive shattered a window at a Starbucks in New York City.
Police said Wednesday that the device was made from a small plastic water bottle stuffed with gunpowder or a similar substance. It had a metal cap with a hole in it for a fuse.
The blast happened on Manhattan's Upper East Side early Monday. Police believe someone put the explosive under a bench outside the coffee shop.
No security video so far shows any suspects, and no one has taken responsibility. But the witness has told police he saw the teens run eastward.