Part of the Prince of Wales Bridge has closed due to a road traffic collision.
A statement posted on The Severn Bridges' Twitter this morning said a crash happened between junction 22 (M49) and junction 23 (Magor) of the westbound carriageway.
Avon and Somerset Police and Avon fire service are at the scene, and lane closures are in place as a result.
It said: "M4 PrinceOfWalesBridge westbound J22 M49 to J23 Magor we are on scene alongside [Avon and Somerset Police] and [Avon fire] with a Road Traffic Collision. There is lane closures in place, please pass with caution."