Police in Oregon and Washington are investigating incidents involving ballot boxes that were intentionally set on fire.

On Monday morning, Portland Police Bureau officers responded to a reported fire at a ballot drop box on the 1000 block of Southeast Morrison Street.

By the time officers arrived, security guards had already extinguished the flames.

Authorities indicated that the fire was started with an incendiary device placed inside the ballot box. Portland’s Explosive Disposal Unit was called to the scene to assess and safely clear the device.

Meanwhile, police in Vancouver, Washington, are investigating a similar incident that took place on Monday morning at the C-TRAN Park & Ride at Fisher’s Landing Transit Center.

According to witnesses, a device placed outside the ballot box ignited the fire, causing hundreds of ballots to burn.

Officials noted that the last ballot collection from this box was at 11 a.m. on Saturday, suggesting the fire had affected a significant amount of uncollected ballots.

These incidents follow a similar case in Arizona last week, where a fire broke out just before 1:30 a.m. on October 24 outside a post office near 7th Avenue and Indian School Road.

Phoenix Fire crews arrived on the scene and quickly extinguished the flames, though the fire damaged twenty electoral ballots along with other pieces of mail.

Phoenix Fire Captain Rob McDade reported that the Postal Inspector took possession of the damaged ballots and mail.

The Phoenix Fire Investigations Task Force, which includes Phoenix Police detectives and fire investigators, is working closely with U.S. Postal Inspectors to investigate the cause and intent behind the incident.