At least four workers died and nine were injured on Sunday after a blast at a chemical plant near Vadodara led to a fire, PTI reported.

The blast took place around 5.30 am at a plant of fertiliser company GSP Crop Science Private Limited, a police official said. The plant is located in the Gujarat Industrial Development Corporation zone at Nandesari.

District Collector P Bharthi confirmed the death of four employees. The injured were taken to hospital. She said the district authorities have ordered an inquiry. The cause of the blast is not known yet.

The fire was doused in around two hours, a police official was quoted as saying.

“After the blast in the plant, fire spread to the other plants as there was flammable chemical substance there,” fire officer Om Jadeja told The Indian Express. “The primary reason for the blast is some malfunctioning in the plant, which led to heavy pressure in the chemical reactor which blasted.”