RICHMOND, Texas -

Fort Bend County Sheriff's deputies have arrested a man who they say shot his own parents dead inside their home.

Ryan Walton, 20, was arrested Saturday afternoon on two counts of murder at the 2-M's Malt n' Burger on Avenue H in Rosenberg.

The arrest came after an off-duty sergeant spotted Walton driving a blue BMW that belonged to his parents, Lynda and Michael Walton.

"And there he was going down, the cops were on him and they pushed him to the ground and cuffed him," said Bill McKinney, owner of 2-M's Malt n' Burger.

After reviewing surveillance video from the Walton home at Lake Pointe Estates in Katy, they saw Walton leaving in the BMW at 9 a.m. Thursday. A few hours later the couple's other son found his parents shot to death inside their home.

"I believe the family did have issues with Ryan," said Fort Bend Sheriff Troy Nehls. "As to the extent of those issues, I am unaware."

"It's horrendous, but you're hearing that everyday on the news," McKinney said. "Kids killing their parents and mass murders and everything."

Prior to the murder, the 20-year-old was last seen at his parent's home about three weeks ago. Nehls said Walton is cooperating with investigators.

Walton is now being held in the Fort Bend County Jail without bond. Investigators still have not found the murder weapon. They plan to search the BMW.