An arsonist set fire to at least 15 police cars at a training facility in northeastern Portland, Oregon, early Thursday morning, authorities said. No one was injured.

Photographs taken at the scene showed huge blazes engulfing the vehicles and a thick mass of grey smoke billowing up from the flames. 

More images taken after the fires were extinguished showed multiple cruisers badly burned, with a sizable hole melted through the hood of one that also had a collapsed front light. The internal frame could be seen on another car that was partly eviscerated. A large propane tank is pictured beside two burning cars in one of the pictures. 

Each torched vehicle was either damaged or destroyed in the incident, the Portland Police Bureau said in a news release. Officers responded to the blazes alongside Portland fire officials at 1:55 a.m. local time on Thursday, according to the bureau. They found a group of parked vehicles burning in a fenced-in area at the Portland Police Training Division, a large complex near Portland International Airport, which is about 10 miles from the city’s downtown. The building itself was not damaged.

A fire investigations unit has opened a probe into what happened, and the police bureau said it is being looked at as a suspected arson case, meaning they believe the vehicles were deliberately burned. The fire investigations unit includes investigators from Portland Fire and Rescue and a detective from the Portland Police Bureau. 

Authorities have not identified any suspect potentially connected to the fires. They are asking anyone with information about the incident to contact the police bureau or the fire investigations unit’s tip line.

Fires that broke out overnight at the training facility were not the first suspected arson incidents on government property in Portland this year. In January, police announced that an arson investigation was underway after a series of blazes burned equipment owned by the city, including a forklift, an excavator and a bulldozer. They said at the time that evidence gathered at the scene “suggested the fires that damaged the equipment were intentionally set.”

The area where those January fires happened is about 20 minutes from the police training facility by car. It is unclear whether anyone has been implicated in the equipment fires, and there is no known connection between that incident and the one at the training facility. CBS News contacted the Portland Police Bureau for comment but did not receive an immediate reply.