Seven persons including three fire officials, were injured on Friday in a powerful blast combined with fire at a chemical factory in Vapi here, police said.
The blast occurred following leakage in an installation vessel in the Arson Chemical factory at the industrial estate, they said.
Valsad superintendent of police D B Vaghela told PTI that all the injured including three fire officials have been admitted to the government hospital and the condition of three persons was critical.
The blast along with the fire has badly damaged a portion of the chemical factory building, the police said.
Fire officials and other forensic experts are examining the site, police said, adding a case has been registered and investigations are on.