The officer was coming out of the game with his family when he noticed some men around his vehicle. He was able to call 911 on his cell phone, but he wasn't able to get help before he opened fire.
One man is in critical condition after being shot in the chin, and the other man is in serious condition after being shot in the arm.
The officer was allegedly hit over the head with an object, possibly a beer bottle, and was also treated for minor injuries.
"What we understand right now is that a couple of guys were beating him over the head with beer bottles, so at that point, he comes back a short time later and calls for paramedics," said Sgt. Rick Martinez from the Anaheim Police Department.
Police are still interviewing many people who witnessed the shooting.
Family members of the two men shot are already disputing the officer's version of what happened.
"The officer just went in, confronted them and start shooting them," said Sandy Bustamonte, one of the victim's sister-in-law.
Bustamonte claimed the officer began the altercation by flipping off the two men.
Beer cans were clearly visible in the suspects' truck, and police believe alcohol was a factor in the incident.
The cause of the shooting is still unclear.
Anyone with information is urged to call the Orange County District Attorney's Office at (714) 347-8814.