A motorcyclist is in a serious condition in hospital after his bike left the road.
The accident happened at the junction of the Downpatrick Road in Ballynahinch, between Cumber Road and Magheralone Road.
The Ambulance Service was called at around 5.50pm and sent a rapid response paramedic and an ambulance.
A spokesman said the motorcyclist left the road and went into a ditch.
He was taken to Belfast's Royal Victoria Hospital.
Diversions were put in place and motorists were advised to seek alternative routes.
There have been a spate of serious and fatal accidents involving motorcyclists over the summer.
Two motorcyclists died in separate collisions with tractors in Londonderry and Fermanagh in April.
Last month a 68-year-old motorcyclist died after a crash in Annahilt, Co Down.
And a 49-year-old from Whitehead also died in July in a collision between his motorbike and a car on the Larne Road, Carrickfergus.