NEW YORK, May 5 -- Two makeshift grenades exploded outside the British consulate here in the predawn hours just as polls opened for national elections in Britain. A large windowpane at the building's entrance shattered, but officials reported no injuries.
The blast occurred at 3:35 a.m. on the sidewalk outside a Midtown Manhattan high-rise that houses various U.S. and foreign businesses. Police officials did not confirm the target of the attack and suggested a possible link to the Israeli-Palestinian conflict. British officials reported they had received no threats before or after the explosion.
Police scan the sidewalk outside the Manhattan building that houses the British consulate after two grenades were set off early Thursday. No one was injured.
(Spencer Platt -- Getty Images)
"We at this point have absolutely no knowledge what the motive was," Mayor Michael R. Bloomberg (R) said. "I don't think anyone should jump to conclusions."
Police retrieved fragments of the devices and said they were two novelty-style grenades packed with gunpowder and attached with a fuse.
Police Commissioner Raymond W. Kelly said a surveillance videotape, which he described as "poor quality," showed a "red arch" of light immediately before the explosion, suggesting the device was thrown against the building and then landed in a barrel-shaped flower box in front of the building.
Investigators also said the grenades may have been planted in one of the concrete flower boxes that line the building's entrance. The blast ripped from the planter a chunk of concrete, sending it through the glass, police said.
A board member of the heavy equipment company Caterpillar Inc. has offices in the building. Police said activists from Jews Against the Occupation protested there last month. Caterpillar has been criticized by activists who say the company manufactures the equipment used by Israelis to demolish Palestinian homes in the West Bank.
Thursday's incident occurred across the street from a police precinct and firehouse. Officers in both departments said they heard the explosion, and a nearby resident described the sound as resembling a magnified electrical transformer explosion. But an investigator at the scene said the intensity of the noise was likely the result of acoustics from the ring of neighboring skyscrapers.
Still, Kelly said the explosion produced a "significant amount of force."
"If someone was in the vicinity, they could have been seriously injured," he said.
Numerous surveillance cameras are mounted on surrounding buildings. Police collected the tapes and interviewed the deli workers and security guards on duty in the neighborhood.
The 14-floor building is located less than a mile from the United Nations. As a precaution, U.N. officials tightened security at the New York headquarters and activated canine teams, said U.N. spokesman Farhan Haq.
No graffiti or signs related to the explosion were visible at the blast site. A few political stickers -- including ones that read England Get Out of Ireland and United Ireland -- are pasted on a street sign in front of the building.
Staff writer Colum Lynch contributed to this report from the United Nations.