One person was killed and three others were wounded in a shooting Tuesday near two polling locations in Azusa, California, CNN reported.
Los Angeles County Fire Inspector Gustavo Medina said one person died after being taken to a hospital.
One polling location was placed on lockdown. It does not appear as though the incident is related to the presidential election.
Azusa is located roughly 30 miles outside Los Angeles.
One male voter told CNN he was inside when he heard a bunch of shots ring out and people from outside starting to run in before officials locked the doors. He told the network a "massive shooting is happening and the police have told us to stay indoors. We are currently on locked down."
A female voter told CNN she heard the shots ring out.
"At first, I thought it was construction but people came running into the room saying they see a guy with a bulletproof vest and a white shirt. As of right now, they just have us in the voting room and are trying to keep us calm," she said.
Pictures sent to CNN from inside the polling station show many people inside, including a group of children who were in the building when the shots rang out.
The shots were not inside the polling station. The background to the incident is under investigation and it is unclear whether the shooting was related to the presidential election.
The LA County Sheriff's Department is assisting the Azusa Police Department with the officer-involved shooting, Sgt. Vincent Plair told CNN.