AMBULANCES are being diverted from the University Hospital of Wales in Cardiff to Newport's Royal Gwent Hospital tonight after a man hit pedestrians with a van.
It is understood there were collisions in at least five different areas of Cardiff this evening.
The ambulance service have confirmed there are at least 12 casualties, including children.
A spokeswoman for the University Hospital of Wales confirmed that ambulances which are not dealing with casualties from the hit-and-run incidents would be sent to hospitals run by Aneurin Bevan Health Board, which includes Nevill Hall Hospital in Abergavenny and the Royal Gwent in Newport.
South Wales Police have said a 31-year-old man has been arrested and his van has been seized.
A Welsh Ambulance Service spokesman said 12 casualties have various injuries, some serious.
"The A&E Dept at UHW has been closed to anything other than casualties related to these incidents," he said. "In the meantime, the ambulance service is liaising with hospitals in the region including the Royal Gwent and The Royal Glamorgan to convey emergency patients."