Four people were injured when an underground water reservoir exploded after coming in contact with candlelight at a residence of the capital's Hazaribagh last night.

Jakir Hossain, 45, the house owner, his son Sabbir Abdullah, 16, tenant Razia Begum, 22, and her one-and-a-half-year-old son Nafis were taken to Dhaka Medical College Hospital.

The explosion occurred when Jakir was checking the water level with a candle during a power outage, said Sentu Das, assistant sub-inspector of Dhaka Medical Police Camp.

Police suspected that trapped gas caused the explosion.