More than 30 vehicles were involved in a pile-up on the M20 in Kent during thick fog on Saturday evening, leaving two people seriously injured and closing the motorway in both directions.

Emergency services were called shortly after 6.40pm to the London-bound carriageway between junctions eight and nine. Paramedics assessed 11 people at the scene. Police said one seriously injured casualty was taken to a hospital in Kent and the other to a specialist hospital in London.

Other motorists and passengers suffered injuries that were not believed to be serious. Police have not released details of those injured, and no arrests have been reported.

Firefighters, ambulance crews and an air ambulance attended. Kent Fire and Rescue Service deployed three fire engines and a technical rescue unit, while emergency crews worked for hours to assist casualties and assess damaged vehicles.

National Highways confirmed there was “thick fog” in the area at the time. The circumstances of the collision remain under investigation; the presence of fog does not, by itself, establish how the pile-up began or developed.

Both carriageways were closed to give emergency services access, allow investigators to gather evidence and enable recovery operators to remove damaged vehicles. Drivers faced major delays on a route linking London with Kent and the Channel ports, used by commuters, freight traffic and leisure travellers.

The motorway reopened on Sunday after recovery and safety work had been completed.

Kent Police are appealing for witnesses and dashcam footage, particularly from motorists who travelled through the area shortly before the crash. Such recordings could help investigators establish the sequence of events that brought more than 30 vehicles into the collision.