A buildup of dangerous gasses continues to prevent rescuers from entering the New Zealand mine in which 29 miners are still trapped after an explosion Friday. Rescuers have been drilling a 500-foot test shaft and are waiting for levels of methane and carbon monoxide to go down — they are worried they could trigger another explosion by entering the mine. No contact has been made with the miners. Each of them carried a 30-minute supply of oxygen, enough for them to reach several days worth of oxygen stores in the mine. They also carried flasks of water, but no food was stored underground.