Five people have been seriously injured and 25 are described as "walking wounded" after a coach carrying tourists crashed off a popular route.
The accident happened on the A83 near the Rest And Be Thankful in Argyll at around 2pm today.
In total, there were 32 people on board the Lochs and Glens Holidays coach.
The serious injuries are not thought to be life-threatening, police said, but the most seriously hurt have been airlifted to the Southern General in Glasgow and the Royal Alexandra Hospital (RAH) in Paisley for treatment.
Police, fire and helicopter rescue crews were sent to the scene and the road has been closed while emergency services treat passengers and investigate the cause of the crash.
Images on social media showed the coach standing upright on an embankment off the A83, next to a stretch of water.
A Police Scotland spokesman said: "Around 2.10pm this afternoon, Thursday March 26, a coach with tourists, overturned on the A83 Rest And Be Thankful.
"It is understood that 32 people were on board, of which five are believed to be seriously injured, but not thought to be life-threatening. They are being taken by ambulance or medevac to either the Southern or the RAH for treatment.
"Twenty-five people are described as 'walking wounded'.
"Emergency services are at the scene. The A83 is closed, with local diversions in place."
A spokesman for the Scottish Fire and Rescue Service said: "Crews from across Argyll are at the scene. Firefighters are working closely with police and ambulance to help people who were on board a coach that overturned."
Lochs and Glens Holidays runs a number of coach trips, mainly in the Scottish Highlands, but picks up passengers across the UK.
The closure of the A83, the main route to Argyll, means motorists face almost 60 mile diversions.
A spokeswoman for Lochs and Glens said: "We are liaising with the emergency services regarding the injured passengers and to establish the cause of the accident.
"In the meantime, buses have been provided to transport the remaining passengers back to their hotel."
Transport Minister Derek Mackay said: "Scottish ministers have been kept fully informed of this serious incident across the afternoon and our immediate thoughts are with the passengers who have been transported to hospital.
"The emergency services have been working closely with helicopters from both Prestwick and Lossiemouth as well as mountain rescue teams and a rest centre has been set up in 'Three Villages Hall' in Arrochar to help the walking wounded.
"The A83, at The Rest And Be Thankful, remains closed to allow the investigation into what caused the accident to get under way."
Artist and local gallery owner Stuart Herd witnessed the accident.
He said: "It was more serious than I first thought, it was pretty nasty. It seemed to slide down the embankment."