Around 6:15 p.m. Friday a call came in for a fire at AIM recycling, which shares its location with Kenny U-Pull on North Broadway.
Employees from Kenny U-Pull say they saw smoke and called 9-1-1 and evacuated the area.
When fire crews arrived, there were flames visible.
Eventually the structure was fully involved, with billowing black smoke and flames reaching dozens of feet into the sky.
Firefighters say the fire started in the environmental area, where workers take gas and fluids out of cars before they're processed.
Officials say there were gas tanks and other flammable liquids in and around the building. Employees say they overheard explosions.
Another obstacle was getting water to the scene. Officials say the closest hydrant to resupply the tankers was about 3 miles away.
"Where we did have a limited supply of water, there was a lot of the tanks that they store the oil and gas in were very close the building, propane tanks, so we concentrated our water when we first arrived to keep those tanks cool because they were starting to vent," said Bangor Asst. Fire Chief Anthony Riitano.
Officials say mutual aid was crucial in knocking down the fire.
Crews from Bangor, Levant, Hermon and Glenburn were among those battling the flames.
No one was inside at the time and no injuries have been reported.
No word yet on the cause of the fire.
The fire marshal has been notified and will be on scene Monday to investigate.