Two motorways have been shut after human remains were found on the road.
Several drivers reported a body on the carriageway between junctions 20 and 21 of the M4 – between Almondsbury and Awkley – at about 6.40pm this evening.
The body is believed to be that of a man in his forties, whose next of kin have been told.
A police investigation to establish how the person came to be on the motorway continues.
Parts of the M4 and M48 motorways near Bristol are likely to remain closed until the early hours of Sunday morning, Avon and Somerset Police said.
In a statement, the force said: “Police are keen to hear from anyone who was travelling along that stretch of the M4 has any relevant information or dashcam footage.”
The road closures were likely to cause significant delays in and out of Wales tonight, with closures starting on the English side of the Prince of Wales Bridge and the Severn Bridge.
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National Highways said the M4 is shut in both directions between junctions 20 and 21, while the M48 eastbound is closed from junction 1 near Aust.
The links from the M5 junction 15 south to the M4 junction 20 west, and the M5 junction 16 north to M4 junction 20 west were also closed.