Portland fire officials are investigating a fire at Triram Connecticut Asphalt.
Crews were called to the scene around 7:30 a.m. on Sunday morning at 171 Brownstone Ave.
Officials from the state Department of Environmental Protection also responded to the scene to investigate whether oil leaked into the Connecticut River.
They said on Sunday there was no evidence of oil in the river but have deployed containment booms as a precaution.
According to the DEP, the fire was in a shed with a heater that is used to warm oil products used to make asphalt.
The asphalt company has hired an environmental contractor to help clean up and the DEP remains on the scene.
The fire is currently under investigation.
Fire crews from Glastonbury, East Hampton and Middletown were called in to assist with the fire.
According to the town’s First Selectwoman Susan Branfield, divers attending a scuba class nearby first reported the fire.