Hundreds of United States election ballots have been ruined after two drop boxes were destroyed – one in Oregon and one in Washington state – in incidents that authorities believe are linked.

One of the boxes was targeted in Portland, Oregon in the early hours of Monday, and a few hours later, another was targeted in Vancouver, Washington.

Incendiary devices were attached to the outside of the boxes and the FBI has been called to help with the case.

“It’s heartbreaking,” said Greg Kimsey, the elected auditor in Clark County, Washington, which includes Vancouver.

“It’s a direct attack on democracy,” Kimsey told reporters.

Both of the boxes had a fire suppression system. But the one in Vancouver appeared not to have worked properly and was unable to stop hundreds of ballots from being destroyed, according to Kimsey.

At a press conference in Portland, officials said enough material from the incendiary devices was recovered to show the two fires on Monday were connected.

They believe they are also linked to an October 8 incident, when an incendiary device was placed at a different ballot drop box in Vancouver. No ballots were damaged in that incident.

Officials in Portland believe just three ballots were destroyed in the attack.

Race for Washington’s third congressional district often heated

Taking place less than 10 days before Election Day, the incidents triggered anxiety among many, as well as a hope they would not be repeated.

The city of Vancouver is the largest community in Washington’s third congressional district, where Democrat Marie Gluesenkamp Perez is trying to hold off a challenge from Republican Joe Kent.

Kent, a one-time member of the US military’s Special Forces, has the backing of Donald Trump.

The battle for the seat, which Perez won by fewer than 3,000 votes when she beat Kent in 2022, has often been heated.

Perez, who runs a car repair company, says she is one of the few working-class members of the US House of Representatives.

Both Perez, 36, and Kent, 44, denounced the attacks and vowed they would not be stopped.

The Democrat said she had requested there be a police presence at all ballot drop boxes in Clark County until Election Day.

“There is absolutely zero place in our democracy for political violence or interference against our fellow citizens, election workers, or voting infrastructure,” she said in a statement.

“I hope the perpetrator of this reprehensible act is quickly apprehended – and local and federal law enforcement have my full support in working to keep our democratic process safe and secure.”

She added: “Our right to vote needs to be protected under all circumstances. We can’t yield to intimidation.”

Kent urged his supporters not to be intimidated, and said it should not deter anyone from voting.

“I condemn these attacks against our democratic process. I know everybody else out here in southwest Washington does as well,” he said in a video posted on X.

“I have full confidence in our law enforcement that they’re going to get to the bottom of this. Stay focused.”

It was later reported that surveillance cameras had captured a Volvo pulling up to the drop box in Portland shortly before security personnel nearby discovered a fire inside the box.

‘Will not tolerate acts of violence’

Ballot drop boxes have faced increasing criticism from Republicans and have been the focus of baseless conspiracy theories, tied to former President Donald Trump’s false claim that the 2020 election was rigged.

The boxes, designed to be tamper free, are often installed outside places such as election offices, libraries and other government buildings, for people drop off their ballots.

Six Republican-dominated states – Arkansas, Mississippi, Missouri, North Carolina, South Carolina and South Dakota – banned their use after 2020.

On Monday, the office of Washington Secretary of State Steve Hobbs said that if a returned ballot was not marked as “received”, voters could print a replacement ballot or visit their local elections department for a replacement.

“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,” Hobbs said.

“Despite this incident, I have complete confidence in our county elections officials’ ability to keep Washington’s elections safe and secure for all voters.”