One driver on the M6 between Wigan and Manchester saw a burning caravan on the road. He tweeted a photograph of the caravan and wrote: "Just past this on the M6 southbound after Charnock services. Caravan on fire not nice to see."

       One witness to the incident on Twitter replied, "we just got through as the flames engulfed".

       They added: "It all happened so quickly."

       Another motorist on Twitter described the scene as being "gridlocked".

       They added: "Haven't moved in 25 minutes."

       More to follow...