At least six people have died and 11 more have been injured after a bus overturned on a highway in south-western Colombia on Saturday. The National Police said a report suggests the driver may have nodded off at the wheel, causing the vehicle to leave the road and overturn onto its left side on the Garzon-Neiva highway in the department of Huila.

Footage circulating on social media showed emergency personnel tending to injured passengers, while distressed onlookers wept beside the wrecked bus. The vehicle, which was heading to the capital, Bogota, was later removed from the road and traffic was restored. None of the victims have yet been formally identified.S1S2

Investigators believe the driver may have experienced a "microsleep", losing consciousness for a few seconds, though authorities were still working to establish the precise circumstances of the crash. Col. Edwin Correa, director of the police's traffic and transportation division, stressed in the report that drivers must ensure they have had "adequate rest before beginning a journey."S1S2

The bus had set off from the community of San Vicente in Colombia's southern department of Caqueta. A statement from the Huila Traffic and Transportation Police said the driver "lost control" of the bus, apparently due to the microsleep. Ariel Perdomo, manager of Cootranscaquetá, told El Tiempo that it was difficult to speculate on the cause and that the company was limiting itself to the police account of the accident.S1S2