UPDATE: Fire and police crews remain on the scene, all other first responders have left.
Crews are on the scene of a serious school bus crash Thursday morning in Butler County, leading to a "mass casualty incident."
Breaking News on KDKA Radio:
The accident sent the bus into a tree on Three Degree Road in Adams Township. The driver was injured, along with several students.
The extent of the injuries is unknown at this time, but the Cranberry Eagle reports the driver was "not alert" after the crash and at least two students and the driver were taken to Pittsburgh hospitals.
Up to 40 students were on the bus at the time of the crash.
Multiple emergency crews were called to the scene and the road is closed in the area. The mass casualty incident was declared to get more crews on the scene.