BEIJING -- China's Ministry of Emergency Management on Sunday said it has sent a working group to aid rescue work following deadly traffic accidents that left nine dead and seven injured on Saturday night in Northwest China's Xinjiang Uygur autonomous region.

The accidents happened at around 10 pm on different sections of an expressway in the city of Usu in Tacheng prefecture, where multiple vehicles crashed in succession. In total, five large vehicles and seven smaller cars were involved.

Local officials said the crashes occurred amid sudden heavy fog, combined with sub-zero nighttime temperatures that caused road surfaces to become wet and icy within a short period of time.

The ministry has called for scientifically organized rescue operations to prevent secondary accidents, urged full efforts in treating the injured to minimize casualties, and emphasized the need for a swift investigation to determine the cause and learn from the incident.