Police combed surveillance footage Tuesday and hunted for additional video that might have captured a small explosion near a Starbucks on Manhattan's Upper East Side.

The blast bore resemblances to previous small bombings in the city, but investigators so far believe it was isolated.

The explosion early Monday destroyed a sidewalk bench and shattered windows; no one was injured. The coffee shop, near the Guggenheim museum, was open Tuesday morning, although the windows hadn't been fixed. Traffic was back to normal in the area.

Issam Hage, a witness to the scene, told MyFOX NY he saw two suspicious looking teenagers seconds before the blast.

"At that time, I didn't know what they were doing. They walked over to the bank and ran out," said Issam.

NYPD reportedly has surveillance video from several blocks away, showing two young teenagers holding a small plastic container, MYFOX NY reports.

Starbucks said in a statement Tuesday that customer and employee safety is its top priority but that it can't discuss specifics during the investigation.

Investigators were analyzing shards of white plastic found at the scene to determine how the explosive device was made. No suspects have been identified.

It wasn't clear yet whether the blast was related to other explosions 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 bicyclist was seen in the area before the explosions. No one of interest has been identified in the surveillance footage viewed by investigators, police said Tuesday.

Police also were looking at whether the Starbucks, based in Seattle, was the target. The Starbucks Corp. is the world's largest gourmet coffee retailer, with more than 15,000 stores, according to a 2008 profile on its Web site.

Click here for more on this story from MyFOXNY.com.