BEIJING (AP) — A passenger coach crashed into the wall of an expressway tunnel in China's northwest, killing at least 36 people and injuring 13 others, official media reported Friday. The injured were sent to the hospital and rescue efforts were ongoing.

The accident occurred in Shaanxi province late Thursday as the coach was on its way to Luoyang, a city in central China, from Chengdu, the capital of the southwestern province of Sichuan, the Xinhua News Agency reported, citing the provincial police bureau.

More details were not immediately available, and it wasn't clear if the coach was the only vehicle involved

Minister of Public Security Guo Shengkun ordered a swift investigation into the accident, according to state broadcaster China Central Television.

Highway accidents are common in China because of high speeds, aggressive driving and a failure to leave adequate braking distance. The World Health Organization estimates that traffic accidents kill around 260,000 people in mainland China each year — a rate of 18.8 in every 100,000 people.