A 78-year-old grandfather shot and killed his 26-year-old grandson in the Renton Highlands last weekend.

According to Renton police, units were dispatched Saturday evening at 11:30 p.m. for a physical domestic situation.

Cmdr. David Leibman, public information officer for Renton, said the call was for a fight involving a mother, son and the mother’s father.

There were two others present in the home at the time of the incident.

As police were en route to the call, it was updated to domestic violence with a weapon.

The grandfather told dispatch he had just shot his grandson.

According to Renton police, the grandfather said he saw his grandson assault his daughter and went to get his gun to protect her.

The grandfather said when he returned with the gun, his grandson’s words and actions made him fear for his life. He then fired at the grandson.

The grandfather then put his gun away and exited the house to wait for the arrival of Renton police.

According to the police log, the grandfather “was contacted outside the residence and was compliant through the entire process.”

Renton police said all parties in the residence agreed the son was a recurrent source of domestic violence to all residents.

“The detectives at the scene believed it was self-defense and didn’t make an arrest,” Leibman said in an email.

Final charging decisions will lie with the prosecutor.

The investigation is still ongoing, he said.