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DELAWARE COUNTY, (CBS) – A 31-year-old man is in police custody after police say he shot his parents in Delaware County.

Police arrested Matthew Hox in Tinicum Township around 3 a.m. Friday.

He is accused of shooting his dad and mom, 77-year-old Henry Hox and 62-year-old Donna Hox, around 8:45 p.m. Thursday on the 400 block of Iroquois Street.

Man Arrested After Shooting Parents, Killing Dad In Tinicum Township: Police

Credit: CBS3

Henry Hox was pronounced dead at the scene and Donna Hox is listed in stable condition.

Mary Ellen Cavanagh says an unusually loud argument in the home next door compelled her to see what was happening around 8:40 Thursday night.

As she came up her neighbor’s steps she heard gunshots and saw something extremely upsetting.

“I could see into the living room through the storm door,” says Cavanagh, “and I saw Donna and I saw her get shot and fall.”

Cavanagh ducked for cover and yelled for her roommate to call 9-1-1. Then walking right past came Matthew.

“He was walking very quick, determined. He didn’t turn to me, he didn’t say nothing, he just walked,” she said.

Police believe the suspect shot his parents during an argument.

After an hours-long manhunt, officers found him about a block away from the crime scene. He was taken into custody at the Prospect Park District Court around 10 a.m.

“Detectives are talking with the victim, Donna Hox at the hospital, she’s providing good information,” said Chief Steve Edmiston with the Tinicum Township police.

Mathew is charged with murder and aggravated assault.

Cavanaugh says the Hox family were nice people and good neighbors. Over the years she’s heard Matthew and his parents argue before but she never expected it to lead to gun violence.

“I’m still shaking, I’m still upset,” she says.