The FBI is investigating two ballot drop box fires that occurred early Monday in the Portland, Oregon area. The incidents involved one box in Vancouver, a small city in Washington state just across the border, and another in southeast Portland.

In Vancouver, local media reported that a device was attached to the outside of the drop box, leading to a fire that burned hundreds of ballots. Meanwhile, in Portland, officials stated that an incendiary device was placed inside a drop box, causing a small fire that damaged three ballots.

During a news conference on Monday, police confirmed that the incidents are believed to be connected and bear similarities to an unsuccessful attempt to set another ballot drop box on fire in Vancouver on October 8.

Ballot drop boxes are used in several US states and cities to allow early voting without standing in line on Election Day. In September, the US Department of Homeland Security issued warnings about social media users encouraging acts of sabotage against these boxes ahead of the election.

Authorities in Vancouver said the last pickup from the targeted drop box was on Saturday morning. They advised anyone who deposited a ballot after that time to contact their local elections office. Greg Kimsey, the official overseeing elections in Vancouver, said the damaged box has been replaced, and efforts are underway to identify and salvage any damaged ballots. Local police will also increase patrols around ballot drop boxes.

In Portland, officials are attempting to reach voters whose ballots were damaged to issue replacements. Police released photos of a dark-colored Volvo believed to be linked to the incidents.

Oregon and Washington are generally safe Democratic states in presidential elections, but Vancouver is part of a closely contested race for Washington’s 3rd Congressional District. Democrat Marie Gluesenkamp Perez narrowly won the seat in 2022 against Republican Joe Kent, and the two are set for a rematch in the upcoming election.

There has been no word yet from police on potential suspects. The BBC reached out to authorities in both cities for further comments.

Washington’s Secretary of State, Steven Hobbs, emphasized the importance of election security, stating, “We take the safety of our election workers seriously and will not tolerate threats or acts of violence that seek to undermine the democratic process.”

Last week, a man in Phoenix, Arizona, was charged with setting fire to a US mailbox containing around 20 ballots. He told police his actions were not politically motivated, but rather an attempt to commit a minor crime to be jailed due to his homelessness. The Phoenix mailbox was for general post, unlike the ballot-specific boxes in Portland and Vancouver.