An 88-year-old American World War II veteran has been beaten to death by two teenagers in an apparently random attack in the state of Washington.

Police found Delbert Belton suffering from severe head injuries in the parking lot of a pool venue he frequented in the eastern city of Spokane.

Belton, who had survived being shot in a leg during the Battle of Okinawa, was rushed to hospital but died hours later.

Police claim the retired aluminium company worker was just about to enter the Eagles Lodge pool venue and play the game he loved, when two men, believed to be aged 19 and 16, assaulted him.

"It does appear random," Spokane police Lt Mark Griffiths told reporters. "It appears he was assaulted in the parking lot and there was no indication that he would have known these people prior to the assault."

Widowed for a few years, Belton reportedly went to the Eagles Lodge at least twice a week, to have a game and meet friends he used to work with at the local Kaiser aluminum factory.

According to his friends, who called him "Shorty", he had never had an altercation outside the lodge before.

"I don't understand how somebody could do this. I really don't," Ted Denison, Belton's best friend for 23 years, told local news channel KXLY.

Belton served in the US Army in the Pacific during WWII. Police are on a manhunt for the two suspects and have released pictures of them taken at the crime scene.

It is the second random killing to shock America in recent days.

Earlier this month 23-year-old Australian baseball player Christopher Lane was shot dead in the Oklahoma town of Duncan by three teenagers.

One of the attackers later told police they decided to kill Lane as he jogged in front of them because they were "bored".