Twenty-nine people have been taken to hospital following two crashes involving a minibus and four cars which has closed a section of the M4 near Cardiff.
The road is shut between junction 33 Capel Llanilltern and junction 34 Miskin following two separate accidents on either side of the carriageway.
One woman has been airlifted to hospital and another 28 people taken to three hospitals by ambulance.
Traffic is queuing for miles and a South Wales Police officer said he believed there would be disruption for a few hours.
Fireman Lee Morley from Swansea was one of the first on the scene; the 27 year-old was driving westbound when he saw the crash happen.
Mr Morley immediately pulled into the hard shoulder. “I jumped over the barrier and a woman in the car which spun out was breathing but unconscious. But I got her to come round by talking to her and doing what I’m trained to do,” he said. “An off-duty nurse then took over from me while I then helped other walking wounded. It was crazy and surreal.”
Mr Morley said two air ambulances attended and one took the injured woman to UHW. “There were children standing on the side of the road, they had been in the cars caught up in it,” he said. “The minibus was full of pensioners and I think they were on their way to see the musical Top Hat in Cardiff. They were mainly walking wounded with some significant cuts and bruises.”
South Wales Fire and Rescue Service said the injured were being taken to three hospitals in the area – UHW, the Princess of Wales in Bridgend and the Royal Glamorgan in Llantrisant. Eyewitnesses caught up in the disruption said traffic was gridlocked.