STARS and emergency crews responded to a serious crash on Highway 93 about 20 kilometres north of Lake Louise on Thursday afternoon.

Emergency crews were called out at about 11:50 a.m. to a collision on the highway near Hector Lake between a sedan and a charter bus.

Officials with Alberta Health Services say four people in the vehicle were injured .

A 20-year-old woman was flown to Foothills Medical Centre by STARS in serious but non-life threatening condition and is now stable.

Three others were taken by ground ambulance to hospital in Banff in stable, non-life threatening condition.

An initial investigation indicated that the coach was travelling north towards Jasper and the sedan was travelling southbound when the collision happened.

The driver of the bus was not injured and there was no one else on the bus at the time of the crash.

Police say road conditions are believed to have played a part in the crash and that alcohol and speed were not involved.

RCMP say the bus is operated by Brewster Transportation which is based out of Banff.