IRNA � A huge explosion took place in a coal mine in Azadshahr region in this northeastern province on Wednesday, said a provincial official.

Deputy Governor of Azadshahr told IRNA on a phone contact that aid workers have been dispatched to the site of the blast in Zemestanyurt coal mine. According to reports the blast was highly serious.

However, Gholam-Reza Qaazavi did not comment on the time and cause of the explosion or its possible casualties.

Meanwhile, one of the officials at the Azadshahr coal mine told IRNA that there is concerns over the health conditions of the miners as the explosion happened at the time of changing the shifts.

However, said Ali Nasiri, nothing is clear yet.

Over 500 miners work at Azadshahr coal mine, 14 km of Azadshahr city which situated in 90 km east of Gorgan, the capital city of Golestan Province.