Three miners have been reported missing after a controlled detonation at a potassium mine in eastern Germany led to a gas leak there.

The German news agency dpa quoted an unidentified official at the mining company, K + S GmbH, as saying that carbon dioxide was released by the detonation Tuesday in the mine in Unterbreizbach in the state of Thuringia.

The official said two mines and the shaft installations above ground had to be evacuated, and that the gas leak led to a large release of dust inside the mine where the detonation occurred and above ground.

Dpa said seven miners were initially trapped but four of them quickly rescued without injuries. Rescue personnel were searching for the three missing miners about 700 meters (about 2,300 feet) below ground.