The 3:22 p.m. fire, in a vacant building on the former Lawrence Aviation property at 100 Sheep Pasture Rd., disrupted service for several hours on the nearby portions of the Port Jefferson line of the LIRR.
Brendan Pilkington, second assistant chief for the Terryville Fire Department, which was the lead department in battling the fire, said crews arrived to find the main building at the shuttered federal Superfund site engulfed in flames, with fire through the roof.
Pilkington said about 100 firefighters from several departments contained the fire to the north side of the building, which housed the administration area. The Town of Brookhaven used an excavator to knock down the front concrete wall of the structure to enable firefighters to continue extinguishing the fire, he said.
Two Terryville firefighters were transported to a hospital for observation, Pilkington said.
Service on the Port Jefferson branch of the LIRR was suspended for several hours, because crews had to drape a water supply line across the tracks, he said. Firefighters were at the scene until midnight.
The building was the scene of several blazes in 2011 that destroyed a building once used to house workers on the 126-acre site, as well as an abandoned office building at the location.
"Not much left to burn up there," Pilkington said.
The Brookhaven fire marshal's office was investigating, as were arson detectives, he said.