New York ? An early morning explosion, caused by a small bomb and reminiscent of other mysterious blasts around the city in the last few years, destroyed a sidewalk bench and shattered windows in a Starbucks coffee shop.

No one was injured in the blast, which happened around 3:30 a.m. Monday on Manhattan’s Upper East Side near the Guggenheim museum.

Investigators were looking into the similarities between the explosion and three others in the last four years, police Commissioner Ray Kelly said.

“They all happened between 3:30 a.m. and 4:30 a.m., so that’s the immediate similarity that we’re looking at,” Kelly said. “Obviously we’re going to analyze the type of explosive that’s been used.”

The bomb went off around the same time of day as an explosion at the British consulate in May 2005, another at the Mexican consulate in October 2007 and one at the Times Square military recruiting station in March 2008.