The fire broke out at Ultra Pure Chem in the industrial colony at around 9.30 AM. The workers immediately vacated the plant, fire officer Suresh Shinde of Dombivali fire station said.
Fire tenders and more than 125 firemen from Mumbai, Thane, Navi Mumbai, Ambernath and Kalyan-Dombivali rushed to the spot and brought it under control after nearly five hours, he said.
Nobody was injured, but the four-story plant was thoroughly damaged, Shinde said.
Kalyan-Dombivali Municipal Corporation commissioner E Ravinderan also visited the spot.