SOUTH Wales Police is at the scene of a single-vehicle collision on Gellifowy Road, Pontardawe.
Emergency services were called at approximately 12.45pm.
One casualty has been taken to the University Hospital Wales with serious injuries.
Three other people have also been injured in the collision.
The road is currently closed from its junction with Ynysmeudwy Road. Motorists are advised to avoid the area until further notice.