HOUSTON -- A 3-year-old boy watched as his father killed his mother and then turned the gun on himself, deputies told KPRC Local 2.

Harris County sheriff's deputies said the murder-suicide took place in front of a home on Duncannon Drive in the Woodforest neighborhood in northeast Harris County at about 11:30 p.m. Wednesday.

Casey Pelfrey's boyfriend, George Shaffer, 21, showed up unexpectedly at the home where she was living with relatives, officials said.

Investigators said Pelfrey, 19, walked up to Shaffer's truck to talk to him. The couple's son was with her and hopped in the truck.

Shortly after talking to her, Shaffer shot her then shot himself, detectives said.

Pelfrey died at the scene. Shaffer was transported to the hospital, where he later died.

Several family members were standing outside the home when the killings happened.

"On occasion, they have co-habitated and have been in an off-and-on relationship," Sgt. Greg Pinkins said.

"She told him that she didn't want to be with him anymore and she didn't want to be with him anymore -- that she needed to get away from him. He scared her and she just needed time. And he said, 'Well, if I can't have you, nobody's going to have you.' And then he shot her and shot himself in front of the 3-year-old son," said Shawna Mueller, the victim's sister.

Investigators said they recovered a shotgun from Shaffer's truck.

Pelfrey's relatives said there was a lot of violence during the couple's four-year on-again, off-again relationship.