NEW YORK (CNN)  -- An explosion outside a Starbucks on the Upper East Side of Manhattan sent frightened people running into the street early Monday.



Police investigate an explosion in a Manhattan Upper East Side neighborhood.



The explosion blew out the windows of a Starbucks coffeehouse at East 92nd Street and Third Avenue at 3:25 a.m., according to New York City Police Commissioner Ray Kelly.



A "low-order improvised explosive device" exploded after being left on a wooden bench in front of the coffeehouse, Kelly said. The blast could be heard many blocks away, according to CNN affiliate WABC-TV of New York.



Seven people were briefly evacuated from the building above the Starbucks, Kelly said, but no one was injured. The interior of the Starbucks sustained no damage.



It's too early to tell whether Monday's incident is connected to other minor explosions in New York City in recent years, including ones at the British and Mexican consulates and another in Times Square, Kelly said.



He did note one immediate similarity between the detonations: All occurred at roughly the same time of night. He said the police would continue to analyze other similarities.



However, Kelly also noted that Starbucks has been the target of low-grade explosions in other cities.



Police plan to examine surveillance cameras for information that could lead investigators to the perpetrator, he said.
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