TRENTON, N.J. -- A frightened father who chased after four men who robbed him and threatened to rape his daughter killed one of the suspects by running him over with a sport utility vehicle, police said.

Police were still searching Tuesday for one of the four suspects who might face murder charges in addition to robbery and weapons violations. The father, 54-year-old Robert O'Neal has not been charged, said Sgt. Pedro Medina.

"Right now it's still under investigation. He's not being charged with anything," Medina said.

O'Neal was robbed at gunpoint outside his home Sunday night, according to police reports. He had just walked his two daughters to the house and returned to his car when he was confronted by the four suspects.

One of them demanded his wallet, and O'Neal handed it over, according to police. Inside were his credit cards and identification.

When the four left, O'Neal jumped into his silver Dodge Durango and chased after them along Route 29.

One of the suspects fired several shots at O'Neal from the back of a station wagon. O'Neal smashed into the suspect's car, and the gunman jumped out and fired two more shots at O'Neal, according to the police report.

During that chase O'Neal ran over the gunman, police said. The dead man was identified by police as 20-year-old Trenton resident Jose Alvarez, an escapee from a Middlesex County corrections facility.

"When they threatened to rape my daughters, that was it," O'Neal told The Times of Trenton for Tuesday newspapers. "They put a gun to my head. I was afraid they were going to come back."

O'Neal said he was simply standing up for himself, and did not plan to hurt anyone. He told CNN that he had only intended to get the suspects' license plate number. He said he didn't intentionally run over the man.

"This (criminal activity) has got to stop," he told the newspaper. "If we don't stand up for ourselves, it won't stop."

Police have arrested Kyle Gibson, 19, of Hamilton, and a 15-year-old whose name has not been released. Charges are being considered, Medina said Tuesday.

He told the newspaper that the suspected robbers could face felony homicide charges because the dead man was slain during the course of a crime.