Serious road traffic collision on the A465 Heads of the Valleys Road near Hirwaun.
South Wales Police are at the scene of a serious road traffic collision on the A465 Heads of the Valleys Road near Hirwaun.
Officers were called to the collision, involving a car and a cyclist, at approximately 14.45pm.
One man has sustained serious injuries and ambulance crews and the Welsh Air Ambulance are also at the scene.
The road remains closed from the A4059 Aberdare junction and the A4061 junction. Traffic is being diverted through Aberdare and Hirwaun village and motorists are advised to avoid the area if possible.
Anyone who witnessed the collision but has not yet given details to officers is urged to contact 101, quoting reference 1700004264.