At least two people have been injured at a Halloween party shooting at the University of Southern California.
Los Angeles police said it remained unclear whether the victims or gunman were students at the university and the gunman was still at large.
Around 100 people were outside the party when four shots rang out, an unnamed student told the Los Angeles Times.
"Everyone started running. I saw a guy who was shot in the leg. He was limping and screaming for his friends to help him," they said.
One victim is believed to have suffered critical wounds to the buttocks and stomach while one to three others suffered minor wounds.
"The suspect is at large. Stay away from the area. Seek shelter in a secure location until the incident is resolved," the university said in an emergency message to students.
"Be aware of your surroundings. If you hear shots fired or have reason to believe that the suspect is in or near your location, notify the Department of Public Safety."
Shots were heard just after 11:30pm California time, with police and the Department of Public Safety arriving soon after.