A man has died after the lorry he was driving crashed off the side of the M4 near the Prince of Wales Bridge.
Gwent Police said the HGV careered down an embankment on to land alongside the Welsh side of the bridge in Monmouthshire at about 10:30 BST.
He was airlifted to hospital in Cardiff but has died of his injuries. No-one else was injured.
The westbound carriageway will remain closed overnight, but the bridge into England has reopened.
Surgeon Charlie Chan said he resuscitated a man he believed was the Romanian lorry driver who was trapped in his cab after the lorry crashed.
“I saw the lorry down the embankment, perched on the rocks so I parked up and ran down while calling 999,” said Mr Chan, who was travelling to Newport from Cheltenham.
“Two other guys, a former firefighter and an off-duty firefighter, were down there and we tried to get the driver out of his cab.
“But he was quite a big guy and we couldn’t lift him out. Initially he had a pulse but his heart stopped so we had to lay him down in the cab and perform CPR.
“I kept doing CPR for about five to six minutes until the air ambulance arrived and took over.
“Thankfully, after the medical team got the right kit and medicine to him, his heart restarted before he was flown to hospital.”
But police said at about 15:30 that the man had “sadly died of his injuries” after being flown to the University Hospital of Wales.
Highways England, which operates the bridge, warned of long tailbacks in both directions between Newport and Bristol after the crash.
Traffic is queuing for six miles on the M5 northbound and about four miles on the M4 westbound.
Beverley Mears, of Highways England, said: “We have been working hard with our emergency services colleagues to reopen the eastbound carriageway.
“Due to the extent of the barrier damage and the complex nature of the vehicle recovery, we are unable to open the westbound carriageway and this will remain closed throughout the evening peak.
“We will continue to work hard to reopen this as quickly and as soon as it is safe to do so.”
Highways England also said 600m (1,950ft) of the central and nearside barrier were damaged in the crash.
Motorists approaching the bridge westbound – between junction 22 and junction 23 on the M4 – will be diverted to use the M48 Severn Bridge overnight, but the eastbound carriageway reopened at about 17:30.
Police officers are appealing for witnesses or anyone with dashcam footage.