SARAJEVO, Aug. 2 (Xinhua) -- Three people were killed and one severely injured after an explosion at a hydro power plant on Thursday afternoon near Bihac, 310 kilometers northwest of Bosnia and Herzegovina's (BiH) capital city.

The accident took place in the Una-Kostela hydro power plant after a gas leakage, an internal affairs spokesperson of Una Sana Canton Adnan Beganovic told local media.

The police in Bihac received a telephone call from the security guard at 1:00 p.m. local time (1100 GMT), informing them that there had been an accident.

The gas leak was inside the facility where workers were working on an overhaul.

The surviving victim was transported to a local hospital and is in critical condition, Beganovic explained.

An investigation is underway to determine the circumstances of the accident, Beganovic added.