PORTLAND, Ore. (KOIN) – Authorities believe the man suspected of setting fires in ballot boxes in Portland, Oregon, and Vancouver, Washington, this month could be planning more attacks. The Portland Police Bureau (PPB) released additional details about the suspect, who remains at large, during a press conference on Wednesday. “We believe this suspect has a wealth of experience with metal fabrication and welding,” PPB spokesperson Mike Benner said. He explained that the way the incendiary devices were constructed and how they were attached to the metal drop boxes showed that expertise. Police described the suspect as a man, aged 30 to 40, who is either bald or has very short hair. He also has a medium-to-thin build. Investigators previously said that surveillance video showed the man driving a black or dark-colored 2001 to 2004 Volvo S-60. The vehicle did not have a front license plate, but it did have a rear plate with unknown letters or numbers. Police are investigating after a fire was started in a SE Portland ballot box (KOIN)(PPB)(PPB)Authorities are investigating a fire that started at a SE Portland ballot box (KOIN) Surveillance images captured a Volvo pulling up to a drop box in Portland just before security personnel nearby saw a fire inside the box on Monday, Benner said. The early-morning fire near the Multnomah County Elections Division office was extinguished quickly thanks to the box's suppression system and a nearby security guard, police said. Only three of the ballots inside were damaged. Within a few hours, police said another fire was discovered at a ballot box in Vancouver. Even though this box also had a suppression system, hundreds of ballots were destroyed. Elections staff identified 488 damaged ballots retrieved from the box in Vancouver. Six of the ballots were unidentifiable, and the office said the exact number of destroyed ballots wasn’t known, as some may have completely burned to ash. Authorities said that enough material from the incendiary devices was recovered to show that the two fires were connected — and that they were also connected to an Oct. 8 incendiary device at a different ballot drop box in Vancouver. No ballots were damaged in that incident. House Republicans take aim at White House response to Biden’s ‘garbage’ comment Laserfab USA manufactures the reinforced steel ballot drop boxes used in Multnomah County. The company's vice president, Larry Olson, said counties buy fire suppression devices separately from other vendors that magnetize to the top or side of the boxes. "And when it senses the fire, basically this opens up and spills fire retardant down below," Olson told Nexstar's KOIN while holding up the Firestop brand fire suppressant. The devices are designed to put out kitchen grease fires. The main reason why they're used in the ballot boxes is because the fire retardant is a dry chemical, rather than water. Election staff on Wednesday planned to sort through the damaged ballots for information about who cast them, in the hopes that those voters can be given replacement ballots. Anyone with information related to this suspect is encouraged to contact police. Crime Stoppers of Oregon is offering cash rewards of up to $2,500 cash for any information that leads to an arrest, and tipsters may remain anonymous. To submit information to Crime Stoppers, visit their website. The Associated Press contributed to this story.