Authorities in Portland, Oregon, and Vancouver, Washington, said they have opened an investigation after two ballot boxes went up in flames early Monday morning.

In Portland, an incendiary device was placed in the ballot box and used to set it on fire, the Portland Police Bureau said in a statement. Police said a suspicious device was found next to the polls in Vancouver, just across the state line and about a 20-minute drive from Portland.

According to the police department, officers in Portland responded around 3:30 a.m. Pacific Time to reports of a ballot box on fire. The mailbox, where voters can cast their votes upcoming electionswas located in southeast Portland, near the Multnomah County Elections Division office, according to CBS affiliate KOIN-TV.

When officers arrived, the fire had already been extinguished by security guards working in the area. Officers discovered an incendiary device in the ballot box, which they determined was used to start the fire. According to police, the bomb squad arrived on the scene and cleared the device.

The Portland Fire Investigations Unit is working with the Police Department to investigate the incident.

“The partnership uses the specialized training and skills needed to investigate fires, including analytical equipment and dogs that detect accelerants,” the police statement said.

Authorities have asked anyone with information about the Portland ballot box fire to contact Police Department Detective Meredith Hopper or report tips through the fire investigation unit’s dedicated line.

The Vancouver ballot box caught fire shortly after the Portland one. Vancouver police said they responded around 4 a.m. to reports of a ballot box on fire near the Fisher’s Landing Transit Center.

ABC affiliate KATU-TV published several images showing thick smoke rising from the ballot box, next to burning ballots being emptied onto the sidewalk.

Vancouver police said they extinguished the fire and members of the city’s Metro Explosive Disposal Unit “safely collected” the device. The FBI is investigating.

“The FBI is coordinating with federal, state, and local partners to actively investigate the two incidents in Vancouver, Washington and Portland, Oregon, in the early morning hours of Monday, October 28, to determine who is responsible,” the FBI said in a statement declaration. statement to CBS News.

Clark County Auditor Greg Kimsey told The Associated Press that the ballot box in Fisher’s Landing contained a fire suppression system, but for some reason the system was ineffective. Kimsey said hundreds of ballots were destroyed in the fire, the AP reported.

It was at least the second time in October that Vancouver authorities dealt with an incident like this. Earlier this month, the city’s Metro Explosive Disposal Unit destroyed another suspicious device found near a ballot box early one morning, KOIN-TV reported at the time. Police said the ballot box in that case was not compromised and no one was injured, the station said.