An explosion at a coal mine in northern Iran has killed six workers, according to state media.

The blast took place in a tunnel at a depth of 400 meters (440 yards) in the northern city of Damghan, said the official IRNA news agency. It was not immediately clear what caused the explosion.

“Six miners were trapped underground on Sunday when the coal mine explosion took place in Damghan,” IRNA said.
Efforts to rescue the miners were unsuccessful but the bodies were recovered Monday morning, it added.

IRNA showed footage of other workers at the site trying to recover the remains of their colleagues’ bodies from under the rubble.

In May 2021, two miners died in a collapse at the same mining site, local media reported at the time.

At Azad Shahr city in northern Iran, in 2017, 43 miners were killed after a coal mine blast, triggering anger toward Iranian authorities.