A woman has been air-lifted to the Heath hospital in Cardiff with serious leg injuries, following a crash on the A40 this afternoon.
Emergency services were called to the crash, involving two vehicles, near the Gibraltar Tunnels in Monmouth just after midday.
One of the cars left the road, falling down an embankment into trees. It was driven by a man in his fifties, with a woman and two children as passengers.
The man and children were taken to Neville Hall Hospital with minor injuries
The other car is believed to be a black Ford Fiesta or Ford Focus, being driven by a white man aged between 20-30 years old.
The car was last seen turning left at the traffic lights into Monmouth.
The northbound A40 has been closed and diversions are in place.
Police are asking anyone with information to come forward.
A man has died in a road accident on the A40 in Carmarthenshire this morning.
Emergency services were called to the scene of the accident near Whitland roundabout at approximately 9.20am this morning.
The crash involved a Vauxhall Astra and a motorcycle.
Dyfed Powys Police has confirmed that the male motorcyclist sustained fatal injuries.
The A40 remains closed from St Clears roundabout to Penblewin roundabout, and diversions are in place so that examinations can take place.
Police are appealing for witnesses to come forward.
Emergency services are at the scene of a 'serious' road accident between a car and a motorcycle on the A40 in Carmarthenshire.
Emergency services were called to the Whitland roundabout at about 9.20am this morning.
The road remains closed in both directions.
Police are dealing with a "serious accident" on the A40 at Whitland in Carmarthenshire between the B4328 (Llanboidy Roundabout) and the A478 (Penblewin Roundabout). The road is closed both ways and is likely to remain closed for some time.
All lanes have reopened after an accident on the A40 Southbound between the A466 (Monmouth Traffic Lights, Monmouth) and the A449 (Raglan Interchange, Raglan Castle).
All lanes have been re-opened and the accident cleared on the A40 Westbound between the B4312 Llysonen Road (Carmarthen) and the B4299 (Meidrim / Sarnau).
There's slow traffic and one lane is closed after an accident on the A40 Westbound between Newton Court Lane and the A466 Dixton Road (Dixton Roundabout).
The A40 is closed in both directions after an accident between the A4076 (Scotchwell Roundabout) and the A4075 (Canaston Bridge).
One lane is blocked after an accident on the A40 Westbound between the B4312 Llysonen Road (Carmarthen) and the B4299 (Meidrim / Sarnau).
The A40 is blocked after an accident between the A482 (Llanwrda) and the A483 New Road / College View (Llandovery). Police are directing traffic.