Emergency services have raced to the scene on the junction 30 near Preston after a huge crash, with parts of the road expected to be "shut for some time".
Pictures from local cameras show huge queues building long the major stretch of UK motorway as far back as junction 30 (Blacow Split) and junction 29 (Bamber Bridge).
It is not yet known whether there have been any severe casualties as a result of the crash, which sparked traffic chaos on Friday evening.
A spokesperson for Lancashire Police wrote on X: "We have closed lanes 3 and 4 of M6 Northbound due to a road traffic collision at Junction 31. We anticipate that the road will be closed for some time.
"We'd recommend looking for an alternative route We'll update you here once the road is fully open again."
Express.co.uk has contacted Lancashire Police and North West Ambulance Service for further information.
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