Chinese work safety officials Wednesday were investigating the cause of coal mine collapse that killed at least 18 miners, officials saidRescue workers found the bodies of 16 miners trapped in the state-owned mine in Shaanxi province, reported Xinhua, China's official news agency. Two rescued miners later died in a hospital from what doctors said was gas poisoning.Twenty-eight workers were in the mine when the shaft collapsed, officials said. Crews rescued 12 miners, including the two who later died.Rescuers said they were hampered by heavy smoke and dust in the tunnel. ...