Paramedics were seen working on multiple casualties at the side of the road following a three-vehicle smash on a notorious dual carriageway.
Police, fire and ambulance vehicles, including the air ambulance, rushed to the A90 at Petterden, near Tealing, shortly after 8.15am.
The smash involved a van, car and a double-decker Stagecoach bus.
Eyewitnesses described seeing paramedics working on casualties at the roadside. Fire officers were also providing first aid.
Details of casualties are yet to be released, but the inside lane of the carriageway and the slip road to the A928 towards Kirriemuir remains closed.
A commuter who passed the scene heading into Dundee said the collision looked “quite serious”.
She added: “The bus was sitting across the (A928) junction – the van was on its side, the bonnet totally crumpled up.
“As I came past the paramedics were already working on someone in the road – they must have gotten there really fast.
“As I got down to the roundabout at Struan’s the police were pulling across to close the road off.”
The Scottish Fire and Rescue Service sent three appliances to the scene – two from Forfar and a third from Kirriemuir.
A spokeswoman said: “Crews are using trauma bags (first aid kits) and one hose reel jet.”
A Scottish Ambulance Service spokeswoman said: “We currently have multiple resources in attendance at a road traffic collision.”
Police said: “The extent of injuries is not yet known.
“Traffic is still being badly affected so we still recommend avoiding the area if at all possible.”
A Stagecoach East Scotland spokeswoman said: “We can confirm a van was in collision with one of our buses at the A90/A928 Glamis junction around 8.15am today.
“Our first thoughts are for those involved in the incident.
“We are supporting the police and the emergency services in any way that we can.”
A Scottish Ambulance Service spokeswoman said: “We currently have multiple resources in attendance at a road traffic collision.”
Motorists have been urged to avoid the stretch of road following the crash, with police stating that the road may be closed for some time.
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