A 40-year-old woman has been taken to the Heath Hospital with life-threatening injuries following a collision on the A472 in Ystrad Mynach.
Gwent Police is appealing for witnesses who may have seen the collision at 9.40am Friday.
The incident happened on the A472 near its junction with Lewis Street and involved a grey Renault van and a female pedestrian.
The pedestrian, aged 40, was taken to the University of Wales hospital with serious injuries and is currently in a life-threatening condition.
A 30-year-old man has been arrested on suspicion of dangerous driving and is currently in police custody.
The A472 was closed between its junction with Lewis Street and the roundabout where it meets the A469 while enquiries took place but was later re-opened.
Diversions are in place, however motorists are advised to avoid the area if at all possible.
Anyone who may have witnessed the collision is asked to contact Gwent Police on 101.
The sooner the authorities install traffic lights for both traffic and pedestrians at the junction of Nelson Road and Lewis Street, the better.
We all hope the lady concerned pulls through.
Does anyone know if a new Zebra crossing is going to be put in closer to the Royal Oak pub?