PISCATAWAY - Authorities are trying to determine whether a New Jersey police officer shot himself or was killed by officers during a standoff at his home.

Middlesex County Prosecutor Bruce Kaplan says Piscataway Police Sgt. David Powell, 46, had threatened to kill any officer who approached the home during the standoff which began yesterday afternoon and ended early this morning.

Kaplan says the incident began after Powell refused to report that he violated a restraining order. The prosecutor says Powell claimed he had a hostage.

Officials say Powell died of a gunshot wound sometime after he stepped out onto the porch and opened fire on his fellow officers with a 9-millimeter submachine gun. Investigators say SWAT team members returned fire

A robotic device was eventually sent in and officers determined no one else was in the home.

Neighbor Wendy Richards says that Powell was just divorced by his second wife and perhaps that's what pushed him over the edge.