OKLAHOMA CITY - A grandfather shoots and kills his grandson.

Police say George McPhetridge, 80, and his grandson, 26-year-old David Earl Whited got into an argument late Sunday night in the 3700 block of N.W. 14th Street in Oklahoma City.

Whited was armed with a knife and allegedly attacked McPhetridge. Police say that is when McPhetridge shot and killed his grandson.

McPhetridge suffered a cut to his head during the attack. He was treated and released at a local hospital.

Court records show McPhetridge filed a victim protective order against his grandson in May of 2011. The protective order was dismissed in August of 2011.

The investigation is still in the preliminary stages. No arrests have been made.