Moretti says the first wagon derailed, causing four more to derail, while another nine wagons and the locomotive remained on the track. "From the first evidence, the only visible element is that the axle of the first wagon was broken," says Moretti. "But the wagons had been checked and were in complete compliance with EU standards." GATX Rail Austria, which owns the tank wagons, says it does not know the cause of the explosion. The area has been sealed off in case of further explosions, and search and rescue operations are continuing.