ITV News has been speaking to Davina Payne, who drove past the crash minutes after it had happened.
Traffic was at a standstill past the Brynglas tunnels going Eastbound. The coach was situated between the slip road to Caerleon and the slow lane. I could see passengers standing around - some were still in the coach and there appeared to be a person still sitting behind the wheel. The whole of the front of the coach had been taken off - there was mangled and twisted metal everywhere. There was a white car in the fast lane at a right-angle across the motorway.
More top news
Owen Smith has been sacked from Jeremy Corbyn's shadow cabinet after calling for a new EU referendum.
The former Olympian turned coach has three athletes heading to Australia to compete in the Games.
After facing calls not to try to outflank Labour on the left, the party's leader calls for unity to achieve the aim of ruling Wales.