Five people are believed to have been taken to hospital after a two vehicle collision closed part of the Forfar by-pass.
The crash happened at the Lochlands junction around 2.30pm on Saturday afternoon and involved a silver Ford Fiesta and a Citroen Berlingo van.
Four occupants of the car, including two young children, were taken to Ninewells Hospital.
The female passenger in the Fiesta is understood to be the most seriously hurt, although the full extent of her injuries are not known.
The male van driver was also taken to hospital as a precaution.
Emergency services remain at the scene, with northbound A90 traffic heading to Forfar being diverted to the McDonalds junction.
*UPDATE* 15:00 ⌚️#A90 CLOSED S/B at Forfar due to RTC ⛔️
Traffic being diverted off at Mcdonald's towards Forfar and rejoin #A90 from Dundee Road.
Traffic very slow in the area ❗️— Traffic Scotland (@trafficscotland) July 27, 2019
Southbound traffic is being diverted into Forfar at the A94 junction.
Police have appealed for anyone travelling on the road at that time who may have witnessed the crash, or seen the vehicles involved just prior to it, to contact 101.