Follow CBSPHILLY Facebook  | Twitter

CHESTER COUNTY, Pa. (CBS) — The district attorney for Chester County says the man who shot and killed his elderly parents last week had a “grudge against the world.”

Authorities say 59-year-old Bruce Rogal shot and killed his parents at their retirement home and shot at his wife last Wednesday. He later committed suicide after shooting himself in the head.

Philly Police Arrest 1 Suspect Accused Of More Than 20 Armed Robberies; 2nd Suspect Remains At Large

The shootings prompted a manhunt. Six hours after the initial shootings, Pennsylvania State Police spotted him driving his silver Odyssey.

During Wednesday’s press conference, Chester County District Attorney Tom Hogan showed police chopper footage of the final two minutes of the chase.

Rogal drove back to his ex-wife’s house in West Bradford where he originally tried to shoot her and crashed his SUV into the home.

They say that’s when he shot and killed himself.

Hogan also gave more details about how Rogal killed his parents, Walter and Nancy Rogal, at their home at Bellingham Retirement Community in East Goshen.

‘He Should Do The Time’: Community Reacts To Cosby Sentencing

“The executive director goes up himself to the room, opens the door, and Walter and Nancy are there. At first it looks like they’re fine, sitting in two recliners next to each other just as they had spent decades of their life. They looked perfectly peaceful, but when Ed gets in there he realizes there’s blood on both of their heads and they’re dead,” said Hogan. “They had both been executed, head shots to each one of his parents. Walter and Nancy were dead, killed by their own ungrateful son.”

Hogan says Rogal’s son tried to warn his grandparents before they were killed.

“He called and got his grandmother Nancy on the phone and was telling his grandmother “you’re in danger, my father is on the loose, he shot at my mother, you guys need to be concerned,” and as he’s talking to her the phone goes dead and all of a sudden his grandmother is not there and there’s nothing on the other end of the line,” said Hogan.

Officials say Rogal, who was newly divorced from his ex-wife, was unemployed and had a girlfriend outside of his marriage for the last decade. Hogan says his ex-wife took out a restraining order on him that recently expired.

The exact motive is unclear.

“Which of these things, which grudge set him off: the divorce decree, the argument with his wife, the eviction notice, the argument with the parents, we don’t know,” explained Hogan. “It was one of those things all coming to a head at the same time. The only person that could’ve told us is dead now.”

Police found hundreds of rounds of ammunition in Rogal’s house. Two of his guns are still missing.