Three employees at Aurobindo Pharma suffered severe burns after a reactor exploded at a pharmaceutical plant in the Indian district of Andhra Pradesh today.

According to police in the area, the injured were taken to private hospital in Visakhapatnam, where they are reported to be in a critical condition with over 90% burns.

The employees were working at the generic drug maker’s active pharmaceutical ingredients manufacturing plant when the explosion occurred.

Ranastalam police inspector Venugopal Naidu told PTI, “As per the initial information we received, there was a reactor blast at the facility. Three persons were injured and they were taken to a hospital in Visakhapatnam for treatment.”

Aurobindo Pharma’s manufacturing facilities are approved by several regulatory agencies including the US Food and Drug Administration, the World Health Organization and the UK’s Medicines and Health products Regulation Agency.