The Pacific Northwest has seen back-to-back ballot drop box fires which have destroyed hundreds of early mail-in ballots.

A box located on Morrison Street in Portland, Oregon was set on fire early Monday morning, according to CNN. Officials with the Portland police bureau say that explosive devices were placed inside the receptacles.

“Officers determined an incendiary device was placed inside the ballot box and used to ignite the fire. PPB’s Explosive Disposal Unit responded to the scene, cleared the device, according to a statement from the Portland Police Bureau.

Another ballot box a state away in Vancouver, Washington, was set on fire later Monday morning, according to a report from local news station KPTV, which reports that someone had stuck an unidentified device on the outside of the box to ignite the blaze.

County election officials say that the ballots inside were destroyed, and anyone who dropped off their ballot after 11 a.m. Saturday should contact the Clark County Elections Office. 

FBI officials are investigating the incident.

“Heartbreaking,” Clark County Auditor Greg Kimsey said to The Associated Press. “It’s a direct attack on democracy.”

Vancouver, the largest city in Clark County, Washington, is the most significant source of Democratic votes for the area’s congressional district, according to Five Thirty-Eight’s Senior Elections Analyst, Geoffrey Skelley, in a post on X.

“More specifically, this is in WA-03, one of the most highly-contested House races in the country,” he wrote.

The incidents come as a new report from the FBI and the Department of Homeland Security warns state and local law enforcement “that domestic violent extremists seeking to terrorize and disrupt the vote are a threat to the election and throughout Inauguration Day,” according to a report from NBC News.

Officials identified potential targets including physical attacks on candidates, elected officials, elections workers and violent acts at polling locations, drop boxes, and campaign events.