Investigators are eager to interview the 14-year-old lone survivor of what they suspect was a murder-suicide that left five members of a family dead.

The teen, recovering from surgery for a gunshot wound to his torso, may hold the key to what happened at the condo complex in Yorba Linda, a bedroom community about 40 miles southeast of Los Angeles. The apartment where the shootings occurred is across the street from the Richard Nixon Library.

"At this point, he's the only surviving eyewitness," said Lt. Jack Conklin of the Brea Police Department. Police can't interview the teen until Monday at the earliest because he remained sedated.

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Police responding to the scene late Saturday found five people, including three children, dead of gunshot wounds. The teen's mother was discovered on the doorstep, said Conklin.

Inside the home, police found the bodies of two girls in a bedroom, apparently asleep in their beds. The body of a boy was discovered in another bedroom, along with the body of a man with a shotgun beneath him. Authorities still are trying to determine a motive for the slayings, but believed the father was the gunman.

Based on the number of shell casings found at the scene, investigators concluded that each victim was shot once, Conklin said. The survivor was identified as Ian Mercado. He called 911 and told police that his father shot him and his brother.

The teen gave police a brief statement at the scene, recounting what he told the 911 dispatcher. It appeared the boy was unaware his mother and sisters had also been shot, Conklin said.

The victims were identified as Orland Cho, 41; Maricel Cho, 39; Nicole Cho, 9; Kathleen Cho, 8; and Christopher Cho, 5. Authorities believe the couple were married and Mercado was the woman's son from a previous relationship.

The shooting rampage stunned police and residents of Yorba Linda. Conklin said the region has a low crime rate, with a homicide every few years.

"It's a very, very safe community," Conklin said. "This is very unusual."

On Sunday, coroner officials removed the bodies on a gurney draped in a red sheet while police searched the condo for evidence. Autopsies were planned for Monday.