Two U-Haul rental trucks went up in flames before dawn Thursday, Oct. 29, in a Southwest Portland parking lot that doubles as a ballot drop-off site.

The ballot drop box was not damaged, and investigators said they do not believe the fire is connected to it, as first reported by The Oregonian.

Portland fire and police arson investigators responded to the A-Boy and U.S. Bank lot at the corner of Southwest Barbur and Terwilliger boulevards after residents reported explosions around 4:40 a.m.

A witness told The Oregonian he saw two men carrying what appeared to be gasoline before they drove off in a blue car.

Investigators have not determined a motive and have not ruled out accidental ignition during a gasoline-siphoning attempt, the newspaper reported.

No injuries were reported.

Ballot box undamaged; 2024 arsons still unsolved

The lot at 7365 SW Barbur Blvd. is listed as an official Multnomah County ballot drop-off location, according to KGW.

Oregon's general election is Tuesday, Nov. 3, with ballots due at official drop sites by 8 p.m.

The fire comes two years after ballot-box arsons in the Portland and Vancouver area. On Oct. 28, 2024, incendiary devices were placed on ballot drop boxes in both cities, according to the FBI.

Hundreds of ballots were destroyed at a Vancouver transit center. A fire outside the Multnomah County elections office in Southeast Portland damaged three ballots before security guards and fire-suppression canisters extinguished it, OPB reported.

The suspect in those 2024 cases has not been identified. The FBI is offering a reward of up to $25,000 for information leading to the suspect's identification, arrest and conviction. Tips can be submitted at fbi.gov.

Ahead of the 2026 election, Clark County was installing security cameras at all 22 of its ballot drop boxes in response to the 2024 attacks, KGW reported.