The death toll from the explosion and fire at Sigachi Industries’ SIGC.NS chemical factory in southern India has risen to at least 39, officials said on Tuesday, forcing the supplier of pharma products to shut operations for 90 days.

HYDERABAD, India (AP) — The death toll from Monday’s massive explosion and fire at a pharmaceutical factory in India’s southern state of Telangana has risen to at least 36 while about three dozen were left injured, authorities said Tuesday.

It was not immediately clear what led to the blast at a factory near Hyderabad, but officials said initial clues suggested a pressure buildup in a dryer system.