UPDATE: Grady County Sheriff's Office Issues Silver Alert For Missing Man

The Grady County Sheriff's Office has issued a silver alert for a man who has been missing since 12 p.m. on Tuesday.

Allen Byfield, 74, was last seen at 721 County Road 1310 in Chickasha, Oklahoma. Authorities say he suffers from Alzheimer's disease. He was under proven medical or physical ability, and deputies believe he is in imminent danger of serious bodily injury or death.

Byfield stands 5 feet 10 inches tall, and weighs 180 pounds. He was wearing a blue plaid flannel shirt, a green ball cap, blue jeans, and he wears silver glasses.

He was driving a 2006, silver, 4-door Dodge truck with an Oklahoma license plate 819GZR. The truck's taillight on the driver's side is out. It has a diamond-patterned tool box.

Authorities say Byfield also had a gray Yorkie dog with him.

If you have any information, contact the Grady County Sheriff's office immediately.