HYDERABAD, India (AP) — A big explosion triggered a fire at a pharmaceutical plant in southern India, killing at least 18 workers, police said Thursday.

The death toll rose from 15 as three of the 40 injured in the fire Wednesday in the chemical reactor of the plant in Andhra Pradesh state died in hospital on Thursday, police officer M. Deepika said, adding that some of the injured were in critical condition.

The Press Trust of India news agency reported distressing scenes with the skin of several workers peeling off. Ambulances transported them to the hospital.

Officials suspect the fire was caused by an electrical fault at the plant, according to media reports. State authorities have ordered an investigation.

The explosion occurred at the Escientia Company in the Anakapalle district. The plant is about 350 kilometers (220 miles) northeast of Amaravati, the capital of Andhra Pradesh.

The 5-year-old company manufactures intermediate chemicals and active pharmaceutical ingredients.

As the news of the blast spread, hundreds of people from families of workers rushed to the plant to find out what happened to their loved ones.

Around 380 employees work two shifts at the plant. Many escaped because they were on lunch break when the explosion started the fire.

The plant is in the state's special economic zone at Atchutapuram village, which was established in 2009 with over 200 companies. Anakapalli is adjacent to the port city of Vishakhapatnam, a highly industrialized area with many mishaps, including hazardous chemical leakages.

In the most extensive industrial mishap in the region, 22 people were killed when a blast occurred in the refinery of Hindustan Petroleum Corporation in Visakhapatnam in 1997.

Fires are common in India, where builders and residents often flout building laws and safety norms. Some don’t even install firefighting equipment.

In 2019, a fire caused by an electrical short circuit in a New Delhi factory producing handbags and other items killed 43 people.