WATCH: Two dozen people injured in bus crash near Prescott, Ont.

Ontario Provincial Police say at least 24 people are in hospital, four with life-threatening injuries, following a bus crash in eastern Ontario.

Const. Suzanne Runciman says the bus was carrying approximately 37 people, including the driver and a tour guide.

Runciman says the bus went off Highway 401 and hit a rock cut between Brockville, Ont., and Prescott, Ont.

The Ornge air ambulance service has said it is responding to the scene, which is about 95 kilometres south of Ottawa.

Spokesman Joshua McNamara says at least one person has been taken to Ottawa via air ambulance.

He says another aircraft is on its way to Brockville, Ont., and a helicopter from Toronto and a land ambulance from Ottawa are also headed to the scene.

Ontario Provincial Police say Highway 401 west of Prescott has been closed.

Viewer video from the scene of bus crash on Hwy. 401 near Prescott . Ornge ambulance responding. Initial reports of 30-40 injured. @ctvottawa

— Megan Shaw (@meganshawCTV) June 4, 2018

UPDATE ROAD CLOSURE: #Hwy401 WB west of #Prescott - All WB lanes closed at Edward St (Prescott) due to collision, Emergency Services on scene. ^lm

— OPPCommunicationsER (@OPP_COMM_ER) June 4, 2018