THE M4 is closed in both directions between Junctions 11, Reading, and 12, Theale, following a crash.
Thames Valley Police has described it as “serious” and said that the motorway will be closed for several hours.
Drivers are encouraged to find alternative routes.
Traffic on the A33 was heavier than usual by 10am as a result of the closure.
And Reading Buses have said that passengers should expect delays on the network throughout the day.