A tractor-trailer full of produce caught fire in a South Portland parking lot near the Maine Mall early Thursday, officials said, leaking roughly 70 gallons of diesel and requiring the use of firefighting foam to extinguish the blaze.

The South Portland Fire Department responded to the lot at 380 Gorham Road, where they found the truck, owned by a Californian transportation company, on fire around 12:40 a.m., South Portland spokesperson Shara Dee said in a statement Thursday afternoon.

South Portland firefighters used 47 gallons of aqueous film-forming foam (AFFF) to extinguish a burning tractor trailer near the Maine Mall early Thursday. It is the same firefighting material accidentally released in Brunswick last week.  Photo courtesy city of South Portland

Neither of the truck’s two occupants was injured, though one was evaluated at the scene for smoke inhalation, Dee said. The pair had been sleeping in the cab when it filled with smoke. Neither had a cellphone, so they ran down the street and asked someone to dial 911.

Firefighters determined that the truck’s diesel fuel was burning, and they estimated that 70 gallons were released from the truck during the blaze, Dee said.

Crews extinguished the fire with 47 gallons of aqueous film-forming foam (AFFF) – the same material accidentally released at Brunswick Executive Airport on Aug. 19 – which is known to contain PFAS, or “forever chemicals” as they are sometimes called, Dee said.

Firefighters also laid containment booms to try and catch fuel and foam that may have flowed into a nearby gravel wetland and branch of Long Creek. Despite that effort, Dee said some diesel flowed into both areas. The Maine Department of Environmental Protection, the Long Creek Watershed Management District and South Portland’s department of Water Resource Protection are evaluating the site, Dee said.

Though the fire department does not believe there is an any threat to the public, officials are advising pedestrians to avoid the area until the investigation into the fire and contamination evaluation are complete.

Aqueous film-forming foam is used by firefighters to fight high-intensity fuel fires at military bases, civilian airports, fuel terminals and industrial plants that use a lot of chemicals, such as paper mills. The foam forms a film or blanket over the fire, depriving it of the oxygen it needs to burn.

The burned out truck should be removed soon, officials said. Photo courtesy city of South Portland

Firefighting foam is the most common source of forever chemical contamination in the U.S., according to the Environmental Protection Agency, but PFAS has shown up in trace amounts almost everywhere, from polar bears in the Arctic to dairy farms in Maine.

Even trace amounts of some PFAS are considered a public health risk, federal regulators say. High exposure over a long time can cause cancer. Exposure during critical life stages, such as in early childhood, can also cause life-changing harm.

The gravel wetland is fenced off and the tractor-trailer should be removed soon, the statement said.

“SPFD commented that due to the extensive damage, the cause of the fire may not be determined,” Dee said.