Four labourers were injured in a mysterious blast at health resort Sonamarg in Ganderbal district on Monday , police official said .

The blast site is closely located to the signal centre of Army's High Altitude Warfare School (HAWS).

"An explosion occurred near an under-construction bridge in Sonamarg area this morning. Four labourers working on the project sustained minor injuries in their legs," a police official said.

He said the work on the bridge was being carried out by Border Roads Organisation's Beacon unit.

The official said the cause and nature of the explosion is being investigated. PTI MiJ RT