It happened around 7:50 a.m. CST on Highway 21, about 10 kilometres south of Kerrobert.
Police said two charter buses were travelling together, heading toward the Table Mountain ski facility, when a semi-truck turned onto the highway.
One bus was able to stop, but the second rear-ended the first.
The students aboard the buses were 13 and 14 years old.
The RCMP said 15 passengers were taken to hospital with minor injuries. It wasn't immediately clear how many of the injured passengers were children and how many were adults.
The STARS air ambulance service reported that a helicopter was sent to Kindersley Hospital for a transport, although the agency did not say if that dispatch was related to the crash.
Highway 21 was closed for a while, but was re-opened by 10:20 a.m., police said. The charter buses will be towed away.
All of the students on board the buses were from the high school in Kindersley, police said.