A Bronx man who booby-trapped his apartment with homemade bombs accidentally blew his left hand off Thursday morning, police said, prompting the evacuation of dozens of families from the area while the remaining explosives were dismantled.

The man, John Saperstein, 36, an unemployed construction worker, set off one of the bombs in his apartment in East Tremont shortly before 8 a.m., police said.At Lincoln Hospital, where he was taken for surgery, Saperstein told the police two more bombs were in the apartment, officers said.

But the police found four more explosive devices in the apartment, which was cluttered and squalid. One device was rigged with translucent fishing wire and was primed to explode when the wire was tripped; another was hidden in a flashlight; a third was in a small container the size of a shotgun shell; and a fourth was hidden in a box of baby wipes, police said.

Just what Saperstein - who has a criminal record dating back to 1983 for weapons possession, disorderly conduct and drug possession - was doing with all the explosives puzzled investigators.