Five people have died and a sixth has been seriously injured in a collision between two cars on the M4 motorway.
The Independent Police Complaints Commission (IPCC) has been called in after a collision on the M4 at Newport in which five people died.
Gwent Police have confirmed three men from one car and a couple in a second car died in the early morning crash.
A sixth person has been seriously injured in the crash which has shut the motorway in both directions.
An 18-year-old man has also been taken to the Royal Gwent Hospital in Newport with multiple fractures.
The collision between a Red Ford Mondeo and a Red Volvo 940 happened around 0315 BST on Monday.
Three men in one car died at the scene and a fourth, 18, is being treated in hospital, the ambulance service said.
A couple - a man and a woman travelling in the second car - also died at the scene.
The crash happened on the eastbound carriageway between junctions 25A and 25 in Newport.
The IPCC has said it has been asked to carry out an investigation because of some sort of police involvement
Gwent Police have said the M4 will be closed for some time
The M4 is closed between J24 (Coldra) and J28 (Tredegar Park) eastbound and J24 and J26 (Malpas Road) westbound.
The M4 is closed between J24 (Coldra) and J28 (Tredegar Park) eastbound and J24 and J26 (Malpas Road) westbound.
The Independent Police Complaints Commission (IPCC) said they will be investigating the crash because there was some police involvement before the accident.
Gwent Police has said the motorway will be closed for the foreseeable future, and they are urging motorists to avoid the area.
Gwent Police has said the motorway will be closed for the foreseeable future, and they are urging motorists to avoid the area.
Gwent Police have said the M4 will be closed for some time
Diversions have been put in place along the A48 Southern Distributor road towards Newport.
The crash happened on the eastbound carriageway of the M4 between junctions 25A and 25 in Newport, just before the Brynglas tunnels, at around 0315 BST on Monday.
There are currently tailbacks of up to five miles.
The two cars involved were a red Ford Mondeo and a red Volvo 940.
A police spokesman said: "Every effort is being made to open up the carriageways of the M4 as soon as possible."
Diversions have been put in place for drivers eastbound to leave the motorway at J24 and travel west on the A48 Southern Distributor road towards Newport.
Every effort is being made to open up the carriageways of the M4 as soon as possible Gwent Police
There are currently tailbacks of up to five miles back to J23A (Magor Services).
A police spokesman said: "The closure is expected to last throughout the morning rush hour.
"Accordingly, Gwent Police has advised motorists this morning to avoid the motorway and seek alternate routes at the earliest opportunity, to complete their journeys.
"Every effort is being made to open up the carriageways of the M4 as soon as possible."
Westbound traffic is being diverted off onto the distributor road at J28 and there are seven miles of tailbacks reported back to J30 (Cardiff Gate).
Westbound traffic is being diverted off onto the distributor road at J28 and there are seven miles of tailbacks reported back to J30 (Cardiff Gate).
There are long queues also on the A48M in St Mellons and queues go back to the Pontprennau area in Cardiff.
There is also heavy Traffic on all main roads around the motorway.
The A48 from St Mellons to Tredegar Park is also heavily congested.
Traffic is reported heavy on the A470 southbound into Cardiff from Upper Boat but so far the A449 down to the Coldra has not become congested.
But the A470 northbound is also congested ad driver try to find alternative routes head up the A465 Head of the Valleys.
Traffic on the A465 is also reported as being congested.
Last month the M4 was closed around Newport for many hours after a lorry driver died in an accident at Tredegar Park.
Last month the M4 was closed around Newport for many hours after a lorry driver died in an accident at Tredegar Park.
At their worst, tailbacks for drivers after that crash reached 10-miles.Are you caught up in the accident? Please send us your comments using the form below.
At their worst, tailbacks for drivers after that crash reached 10-miles.Are you caught up in the accident? Please send us your comments using the form below.
