Authorities on Monday (October 28) said they had opened investigations into two apparent cases of arson at ballot boxes in Washington and Oregon, just a week from the U.S. election day.

At a afternoon news conference, police said an incendiary device had been placed in a ballot box in Portland, Oregon causing a fire early Monday. Election officials said a fire suppressant system inside the box minimized damage to the ballots.

Officers in neighboring Washington State responded to reports of a similar fire in a ballot box in the city of Vancouver. An incendiary device was also suspected in that blaze, which a CNN affiliate reported had destroyed or damaged hundreds of ballots.

Police said they believe the two incidents are related and released a still image from a surveillance camera showing a Volvo vehicle alongside one of the drop boxed just before it caught fire.

Multnomah County, Oregon Chair Jessica Vega Pederson vowed not to let the incidents interfere with voting between now and November 5th.

"Please do not let this incidents or anything that happens between now and Election Day to keep you from expressing yourself with your vote. Our democracy, our democracy depends on you and you can depend on us to keep this process safe and secure."