Firefighters responded to a fire early Wednesday morning at Casella Waste Systems in Westbrook. Westbrook firefighters say the fire started around 1:30 a.m. in a tractor-trailer outside the facility. The fire then spread to two other tractor-trailers. The fire did not spread to any buildings. Firefighters say the tractor-trailers were filled with compacted trash and kept reigniting. No one was hurt, and there is no word yet on what caused the fire. Follow the Bangor Daily News on Facebook for the latest Maine news.