CHENGDU -- Five people were killed in a traffic accident on Wednesday in the city of Luzhou in Southwest China's Sichuan province, according to local authorities.

The accident happened at around 9:35 am on a national expressway, when a bus carrying 16 people collided with a heavy semi-trailer tractor. The crash resulted in three fatalities at the scene and two additional deaths in hospital, according to the provincial public security department.

Traffic flow at the accident scene has been restored. The cause of the accident is under further investigation.