A small fire broke out in a ventilation system at a Middlefield business on Monday morning.
Middlefield firefighters and crews from area towns responded to Zygo Corporation at 21 Laurel Brook Road in Middlefield around 6 a.m.
Officials said a sprinkler system in the business extinguished the flames.
Some of the plant employees were checked out as a precaution and the building has reopened.
Fire officials are investigating the cause of the fire.
