Two small makeshift grenades exploded outside the British Consulate early Thursday, causing slight damage to the building but injuring no one, officials said. The blasts occurred at 3:50 a.m. (0750GMT) and originated inside a cement flower box outside the consulate in midtown Manhattan, said police department spokesman Noel Waters. Police said the devices were both toy grenades that had been altered to explode by the addition of black gunpowder. Police made the conclusion after piecing together the shrapnel. They estimated that one was the size of a pineapple; the other the size of a lemon. The blasts shattered a panel of glass in the building's front door and ripped a one-foot chunk from the planter. The department's bomb squad was at the scene and streets were closed in the area. Investigators with flashlights searched the sidewalk outside the building before dawn, The Associated Press reported.