The victim, identified as Nancy Corona, 23, of Anaheim, was pronounced dead at the scene from an apparent gunshot wound.
"The apartments are above the parking stall so you actually have to drive in underneath the apartments to park," said Anaheim Police Sgt. Bob Dunn. "The female, who we believe is an adult, was found next to a vehicle in that parking area underneath the apartments."
It's not clear if the woman lived in the apartments or had a vehicle in that garage but nearby neighbors say the only way to get into the garage is if you're a resident.
"We walk by every weekend and that's always locked up," neighbor Tammy Matthews said. "The gates always closed, it's never open so somebody went in with her."
A resident of the South Parks Apartment complex found Corona around 7 a.m. Saturday.
Nick Pond lives across the street and says he came home around 3:30 a.m. and didn't hear or notice anything unusual.
"I came to move my car closer to my house and saw this police line and was a little frightened," Pond said. "And then I heard what happened and, you know, that's very troubling to me."
Some neighbors too frightened to talk on camera said they saw two men running from near the scene about an hour before the body was discovered.
Other residents also said they heard gunshots overnight. But police say those sounds, unfortunately, are very common in this area.
"We are kind of on the fringe here of a gang neighborhood that is right behind us so, unfortunately, the shot fired calls are very frequent in this particular area," Sgt. Dunn said.
Anyone with any information regarding the murder was asked to call Orange County Crime Stoppers at (855) TIP-OCCS or (855) 847-6227.