A Texas man killed his girlfriend and her two daughters before turning the gun on himself, ABC13 reported.

Investigators are still figuring out what caused the 36-year-old Samuel Morales to kill the three females in Fort Worth, according to Crowley Police Chief Luis Soler.

Samuel shot his 34-year-old ex-girlfriend Xiomara Leon and her 18-year-old daughter Linda Gonzalez multiple times on Sunday. He strangled the 13-year-old daughter Yasmine Zavala.

Xiomara's 9-year-old son witnessed the attack and was not physically harmed. He called a relative who then called police to come to the scene.

On Christmas Eve, another Texas man drove 15 hours to Florida and shot his ex-girlfriend's parents before turning the gun on himself, USA Today reported.

That man, 23-year-old Preston Pollard, killed the 36-year-old Richard Hutson of Marion Oaks, while his 55-year-old wife Mary Lou Hutson was taken to a local hospital in critical condition.

Pollard was a recent graduate of the Air Force basic training and recently bought a ticket for the 18-year-old ex-girlfriend who was supposed to spend the holidays in Texas.

"I know my son. That's not him," said Stephen Pollard, Preston Pollard's father. "He was not a mean person."

Pollard said that the 18-year-old was still his son's girlfriend and that he thinks Preston went to go get her when he learned that she was not going to come see him.

Marion County Sheriff's Office spokeswoman Lauren Lettelier said when the girlfriend's father and stepmother opened their door, Preston just started shooting.

Mary Lou was shot four times while Richard Hutson was shot just once. It is believed that the stepmother was the primary target.

"Something went wrong," Stephen Pollard said. "Nobody really knows what happened. ... They say he opened the door and started shooting. That doesn't sound very likely to me."

The former girlfriend and three other children in the home were not harmed.