BALDWIN PARK, Calif. (AP) — A fire inside an official Los Angeles County ballot drop box is being investigated as arson. Authorities say Monday the incident has been reported to the FBI.

The fire was reported Sunday night in the curbside box outside a library in suburban Baldwin Park.

Firefighters put out the fire and pulled out envelopes, some charred. The county registrar-recorder’s office says the items are being reviewed for notification of voters whose ballots may have been impacted.

Ballots were last collected from the box shortly after 10 a.m. Saturday, and voters who dropped off ballots after that were asked to call the registrar recorder.