The M61 was been shut in both directions heading to and from Preston.
Lancashire Police and Highways England shut the motorway due to a concern for safety.
The police incident was centred around the motorway junction at 8 for Chorley.
The closure was in place from Junction 8 to Junction 9, northbound and southbound according to North West Motorway Police.
Highways England stated: “The M61 is closed southbound between Junction 9 Clayton Brook interchange with the M65 and J8 Chorley North Link interchange with the A674 due to an ongoing incident being managed by police. The northbound carriageway is closed within J8.”
There were major delays on the M61 northbound from junction 5 and also southbound building from where the M6 junction to the M61 is.
The incident began shortly before 6pm on Monday (June 1).
Highways England reopened the motorways shortly after 8.30pm on Monday.
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