A hazardous materials team was called to investigate a suspicious chemical at building in Lawrence, Massachusetts, on Wednesday evening.
Fire officials said crews were called to the Microsemi Corporation, a tech company, at about 6:30 p.m. when a haze was discovered in the basement and first floor of the Lake Street building. That haze first appeared to be some sort of chemical.
Authorities said the company does use chemicals but was unclear what could have caused the haze which may have started in the basement.
The building was evacuated as well as all the buildings attached.
No injuries have been reported.
Fire officials said the cause may have been a refrigerant but hazardous materials crews remained on the scene later into the night to investigate.