At least 36 people were killed and another 13 injured late Thursday after a long-distance passenger bus crashed into a concrete wall on a Chinese expressway. The cause of the crash in Shaanxi province was not immediately known, but no other vehicles were said to be involved in the incident. Photos from the scene showed rescue workers towing the mangled bus out of the tunnel where it crashed, and authorities said two children were among the dead. All of those injured in the crash were being treated in a local hospital, though the extent of their injuries was not known. An investigation has reportedly been ordered into the accident.