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.
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Wales head coach Rob Howley admitted his side's performance 'simply wasn't good enough' against Scotland this afternoon.
It will be cloudy with outbreaks of rain at first, but most of the rain will clear by morning.
Despite leading at half time, Howley's men failed to score in the second half with Scotland racking up 20 points to seal the win.