BOGOTA, Colombia (AP) — A bus overturned Saturday on a highway in southwestern Colombia, killing at least six people and injuring 11, the National Police said.

A police report seen by The Associated Press said the driver may have briefly fallen asleep at the wheel, causing the incident.

Videos shared on social media showed emergency personnel assisting injured passengers and people crying next to the overturned bus on the Garzon–Neiva highway. The bus, which was headed to the capital, Bogota, was later removed from the road and traffic was restored.

The police report states authorities were still trying to determine the exact circumstances under which the bus overturned in the department of Huila, but they believe the driver may have experienced an episode of “microsleep" — falling asleep for a few seconds.

Col. Edwin Correa, director of the police’s traffic and transportation division, stated in the report that drivers must ensure they have had “adequate rest before beginning a journey.”

Authorities did not immediately identify the victims.

The bus had departed from the community of San Vicente in Colombia’s southern department of Caqueta.