The wreckage of a collision between a bus and a truck spills off the highway in northwest China's Gansu province, Aug 26, 2014. [Photo/chinanews.com]

LANZHOU - Thirteen people were killed and 50 injured on Tuesday afternoon when a bus carrying 61 people collided head-on with a truck on a highway in northwest China's Gansu province.

The accident occurred at about 12:20 pm when the bus broke through the central partition, veered into the opposite lane and crashed into the oncoming semi-trailer truck on a highway in Guazhou county in the city of Jiuquan, the county police department said in a statement.

Eleven of the dead were passengers on the bus, including a child, and two were in the truck. Of the injured, six are in critical conditions, while the other 44 suffered minor injuries. The injured have been rushed to two hospitals.

The overloaded 55-seater bus was carrying seven children.

Pictures on Sina Weibo, the Chinese equivalent of Twitter, show the truck leaning to one side, while the front of the bus is smashed to pieces. The site of the accident was so damaged that it has been cordoned off for repair, according to local police.

The bus, owned by Xinjiang Siping Commercial Trade Co., Ltd in Urumqi, capital of the far western Xinjiang Uygur autonomous region, was en route from Miquan in Urumqi to Guyuan in Ningxia Hui autonomous region.

The Gansu provincial government has dispatched officials and experts to the site for rescue work. An investigation into the case is under way.