ANAHEIM, Calif. (AP) — Donny Hopkins was buying his wife cigarettes at a drug store when a man burst inside and screamed the unbelievable: A serial killer was savagely stabbing a man in the parking lot.

Hopkins, who knew a killer was stalking homeless men, bolted from the store to find a man repeatedly plunging a knife into a Vietnam veteran behind a Carl’s Jr. restaurant.

“I’m yelling as loud as I can, ‘Hey, stop!’ at the top of my lungs. He just kept going and kept going,” Hopkins told The Associated Press on Wednesday as he recounted the Jan. 13 attack.

Fumbling to dial 911 on his cellphone, Hopkins chased the suspect across the Anaheim strip mall and into a mobile home park, where police eventually collared a blood-covered suspect.

Hopkins, a 32-year-old forklift driver, was hailed a hero Wednesday and given a $5,000 reward for his role in the capture of Itzcoatl Ocampo, a former Marine.

Ocampo, 23, an Iraq war veteran from Yorba Linda, has been charged with murdering four homeless men in Orange County over nearly a month. Police fanned out across the county better known as the home to Disneyland and multi-million dollar beachfront homes to urge the homeless to be careful and seek shelter indoors.

Hopkins received the check at a news conference outside the fast-food restaurant where 64-year-old victim John Berry is remembered.