AUBURN, Mass. - A fire at the Casella waste transfer station in Auburn is under investigation.

Crews responded to the scene around 10:30 a.m. Wednesday. The Auburn Fire Department said trash caught fire in one of the compacting units in the main trash room.

Firefighters said a building like this with so much trash inside it makes it hard to investigate where the fire started.

"Lot's of different hazards here," said Auburn fire captain Justin Brigham. "We don't really know what's burning. Casella does a great job at trying to monitor what comes into the building, but in the end, the amount of trash that comes in here, amount of recyclables that come in here, it's really hard to tell exactly what's burning inside the building. That's probably the greatest risk right now. The staff here is doing a great job helping us sort through the recyclables that are burning right now."

The Massachusetts Fire District Seven fire investigation unit was on scene. No injuries were reported.