Two young men died in the gunfire and two other victims were injured. Investigators said they had no idea what caused the gunman to shoot up the bar in the 10400 block of Folsom Boulevard before he fled.

"There were no fights, no disturbances," said sheriff's homicide Detective Ron Garverick. "We don't know what started everything."

Coroner's officials identified the slain victims as Keith A. Lu, 26, of Sacramento, and Vinh Cam Tuyen, 19, also of Sacramento.

Authorities did not release the names of the injured. Garverick said one was treated at UC Davis Medical Center and released. The detective said the other surviving victim was in stable condition at the hospital.

Garverick said there were about a dozen people in the bar at the time of the shooting, but that none could provide investigators with a workable description of the shooter.

The detective said there is no indication the shooting was gang-related.

"Most everybody we spoke to seemed to be decent kids," Garverick said. "They were listening to karaoke. That's about it."

The bar is in a stucco-faced Rancho Cordova strip mall that also has a boarded-up Chinese restaurant, a cardroom, a Vietnamese restaurant, a Russian bakery, a liquor store and an herb and acupuncture shop, among other businesses.

A sign over the Keyhole advertised Monday that it opens at 6 a.m. and that a funk group called The Smoke Band is "coming on Nov. 12."

"It's just a typical, local bar during the day," said the bartender, who gave his name as "Cherry."

"What goes on around here at night, I don't know," he said.

Inside, the lounge is separated into two distinct areas serving respective clienteles. The front side appeals to working-class Rancho Cordova locals. The back portion is separated by a door with a sign over it that says "The Other Room." It has its own bar and karaoke stage.

Patrons said The Other Room plays to an exclusively Asian American crowd. The gunman walked into The Other Room from the parking lot out back and opened fire, investigators said.

The owner of the bar, Edna Shu, declined to comment. She was accompanied by a number of young men who assisted her Monday in lighting several large sticks of yellow incense outside the back door. They also declined to comment.

A woman patron who identified herself as "Scooter" said she has been a customer of the Keyhole for six years. She said Shu usually tends bar in The Other Room.

Scooter said there have been a few minor altercations in the back portion of the bar over the years, with young men squabbling and occasionally getting physical with each other in disagreements about women.

"But it's usually been peaceful and quiet," Scooter said.

A businesswoman in the strip mall, however, said she has witnessed numerous fights in the parking lot.

Monday's shooting was the second karaoke bar slaying in the Sacramento area in less than a month.

On Jan. 20, a man identified as Thuy Thai Ngo, 27, was shot dead outside the Best Friend Chinese Restaurant in the 2700 block of Fulton Avenue. Two men have been booked on suspicion of murder in that case.

One local law enforcement source said the karaoke killings led him to believe "you've got an ongoing battle" between rival gangs.

Sheriff's spokesman Sgt. Rick Gibson, whose agency is investigating both cases, said "anything is possible" but that "right now it doesn't appear there is a relationship" between the Keyhole and Best Friend shootings.