"At this point, it appears to be a robbery," said Santa Ana police spokesman Cpl. Anthony Bertagna. "I don't know what the confrontation was, but whether he didn't want to give up his wallet or they were just going to shoot him anyway, there was a struggle and he was shot."
The shooting happened in a parking structure near a bar in the 200 block of West Third Street.
Investigators said Cheung was at a bar and left with a friend around 1:30 a.m. to get something from the friend's car. On their way back, two men approached them demanding their wallets.
"The one friend of the victim took off running. He was able to get away," Bertagna said. "There was a confrontation between the deceased and the two suspects."
Cheung was shot in the upper torso. He later died at the hospital.
Two suspects are sought in connection to the violent incident.
A description of the suspect or suspects involved in this shooting was not immediately available. Santa Ana police said they have no one in custody.
The crime is a setback for the city of Santa Ana, which has worked hard to revamp its downtown area to attract restaurants and retailers.
The shooting reminds many of what Santa Ana used to be.
"This used to be gang central back in the day," said Santa Ana resident Mike Gao. "The city officials are really weary of stuff that attracts young people."
"Having to hear what goes on here in Santa Ana, sometimes you don't want to come on this side of town," said Patty Garcia of Tustin.