The collision of two school buses in the Blue Mountains during the afternoon rush has left eight people in hospital.

Seven children and a driver were injured when the buses collided near Sun Valley Rd on the Great Western Highway at Warrimoo in the Blue Mountains about 4.15pm on Friday.

One bus was carrying 15 passengers, while the other had 10 children on board when the vehicles collided, police say.

Two children were taken to Westmead Children's Hospital with minor injuries. Five students were taken to Nepean Hospital with minor injuries and for assessment.

One of the male bus drivers was taken to Nepean with an injury to his shoulder.

A number of people are being assessed for injuries.

Vision from Seven News from shows multiple emergency vehicles at the scene, including ambulances, police cars and NSW Fire and Rescue.

The Great Western Highway is closed in both directions with police diverting traffic.