Witnesses say the gunfire started following a mass brawl between two large groups at the venue in the west coast city of Torrance.
Three people have been killed and four injured in a shooting at a bowling alley in California.
Officers had earlier said they were responding to “reports of shots fired with multiple victims down” at Gable House Bowl in Torrance, a coastal city about 20 miles from Los Angeles, shortly before midnight on Friday.
Torrance Police Department urged people to “stay away from the area”.
Officers said three men died at the scene, while two of the four men injured had been taken to hospital. The remaining pair had sought medical attention themselves.
It is not yet known how seriously they were hurt.
The authorities have not released details about what led to the shooting, but witnesses said it followed mass brawl between two large groups.
Wes Hamad, a 29-year-old Torrance resident, was at the bowling alley with his 13-year-old niece and cousin when he saw a “huge fight” break out.
Mr Hamad said the brawl, which lasted about five minutes, blocked the entrance of the bowling alley and escalated into “complete chaos”.
“I grabbed my niece and started running towards the far end of the bowling alley,” he said. “As we were running, we heard 15 shots.”
As he was leaving, Mr Hamad said he saw a woman weeping over a man who was riddled with gunshot wounds in his head and neck.
Jesus Perez of San Pedro, who was inside during the shooting, told the Los Angeles Times: “We just ran into the bar and we just took cover because after the fight we heard pop pop.”
After taking cover for 15 minutes, he said a security guard had escorted him out the back.
The paper reported people outside the bowling alley were visibly shaken with some men vomiting and women crying and screaming.
Meanwhile, anxious family members attempted to cross the police cordon to find out if their relatives were OK.