Three people were killed and four others were left injured after a section of a motorway collapsed in China.

Smartphone footage recorded by passersby shows several vehicles that plunged down after the road collapse in the city of Ulanqab, in China's Inner Mongolia Autonomous Region.

The incident occurred around 7:30pm on Monday, December 25, when a section of the Erguang Expressway gave way, causing four vehicles to plummet into the resulting void, said the regional public security department.

Emergency teams immediately arrived on site to carry out rescue operations after the incident.

City officials revealed that the injured have been admitted to a local hospital for further treatment, while a probe into the cause of the incident is underway.