Drivers cannot use the M48 to hop over the longest river in the UK due to the emergency. The National Police Air Service helicopter has landed to assist with the operation, believed to have been reported at around midday.
Westbound queues have reached junction 1 for Aust, Gloucestershire. Eastbound traffic is back to junction 2 for Chepstow, Monmouthshire.
Drivers are instead advised to cross the river using the M4 – the Prince of Wales Bridge – famous for essentially connecting England and Wales.
It is unclear what exactly has happened in the medical emergency on the M48.
But there are “about 10 emergency vehicles on the hardshoulder by the westbound exit” of junction 1, reports Gloucestershire Live.
The police helicopter had been seen circling for some time before it landed on the road.
Gloucestershire Police has been contacted for comment.
The River Severn flows into the Bristol Channel just past the bridge.
It meanders 220 miles from its source in mid Wales to the estuary.