A predawn blast outside a Starbucks coffee shop in Manhattan was caused by a makeshift device fashioned from a water bottle and the type of flash powder used in fireworks, police said Wednesday.
No security video has been found that shows any suspects, and no one has taken responsibility, said police spokesman Paul Browne. But a "strong witness" has told police two young men dashed from the scene moments after the blast, he said.
One of the teens had blond hair and was wearing a red shirt, the other had brown hair and a gray shirt, he said.
The device was fitted with a metal twist cap with a hole in it for a fuse, Browne said.
Investigators believe the device was planted at about 3:30 a.m. Monday under a bench outside the Starbucks, on the Upper East Side of Manhattan. The explosion destroyed the bench and shattered the coffee shop's windows, but no one was injured. Police have no suspects.
Browne said Wednesday that it was unclear whether the explosion was related to other unsolved blasts around the city in the past four years: at the British consulate in May 2005, the Mexican consulate in October 2007 and the Times Square military recruiting station in March 2008.
So far, the only similarity has been the time; all the blasts occurred between 3:30 a.m. and 4:30 a.m. In the previous bombings, a lone bicyclist was seen in the area before the blasts, caused by either phony grenades or canisters packed with explosive powder.
No was hurt in the previous cases. However, the devices in all four could have "caused serious injury, if not death," Browne said.
The Starbucks Corp., based in Seattle, is the world's largest gourmet coffee retailer, with more than 15,000 stores, according to a 2008 profile on its Web site. It said Tuesday it didn't believe its store was hit intentionally.