One person was killed and at least three wounded in gunfire on Tuesday near a polling station in the Southern California town of Azusa, prompting authorities to lock down the polling place, a surrounding park and adjacent schools, police said.
The suspect was believed to be holed up in the vicinity, the Los Angeles County Sheriff's Department said.
There was no immediate indication that the incident was related to Election Day or the polling station, said Deputy Vincent Plair, a spokesman for sheriff's department.
But the Los Angeles County Registrar and Recorder's office issued a Twitter advisory urging voters to avoid the area around two polling locations, one in Memorial Park and one in Dalton Elementary School, and to cast their ballots at alternate polling sites. Nearby Slauson Middle School was also placed on lockdown.
A dispatcher answering phones at a nearby fire station that also was serving as a polling place said that location remained opened to voters.
Law enforcement officers came under fire and were initially pinned down as they arrived on the scene, about 25 miles (40 km) northeast of Los Angeles, according to accounts from Azusa police and the Los Angeles County Sheriff's Office.
Police initially said two to three people, all civilians, were struck by gunfire around 2 p.m. local time (2200 GMT), though their conditions were not immediately known. A sheriff's sergeant said later that four people had been wounded.
The Azusa Police Department subsequently posted a Twitter message saying that one person had been killed, two were taken to hospitals in critical condition and there was "one additional down near primary residence."