The rescue work for the last 3 trapped miners is continuing in a coal mine in central China. The work has become much more difficult since those still trapped are deeper in the mine and believed to be in poor condition. The rescue team is trying to broaden the passageway so that stretchers can be taken into the mine. So far, 49 injured miners have been lifted to the surface. 7 miners of them were rescued on Friday. Four were reported killed when a rock burst hit Thursday evening in the Qianqiu Coal Mine in Henan Province. A rock burst is a spontaneous, violent fracture of rock that can occur in deep mines. The rescued miners were sent to hospital with most reported to be in good condition.