The Westbrook Fire Department was called to the Sappi paper mill on Monday night after coal used in one of its boilers began smoldering.

Sappi Spokesman Jeffrey Pina said the incident occurred at about 8 p.m. Monday. He said one of the mill’s boilers had been shut down for maintenance and had been restarted on Sunday.

After the boiler was restarted, Pina said coal from the attached pulverizer apparently got stuck in the chute and began to build up. The pulverizer, which breaks up the coal used as fuel for the boiler, continued to rotate and the resulting heat from the friction caused the coal to smolder, Pina said.

Workers at Sappi initially attempted to extinguish the coal themselves, but they were unsuccessful, Pina said. Three Westbrook fire engines were called to the scene and firefighters extinguished the coal with special foam, Pina said.

Firefighters left the mill at about 9:30 p.m., said Pina, and no one was injured and the mill was not damaged. Pina said the boiler and the pulverizer are back working as normal.