Four workers were injured as a boiler of a plywood factory exploded at Barokhada in Sadar upazila early Friday.
Tuhinul Islam, an official of Woodland Plywood Processing Company, said the fire broke out at the factory around 4 am.
On information, a firefighting unit went to the spot and extinguished the blaze around 7 am.
The injured workers were sent to Dhaka for better treatment.
However, it is still not clear what caused the fire, he said.