Traffic has been held on the M6 following two crashes near Preston.
Lancashire Police are at the scene of the two incidents close to junction 31 for Samlesbury.
One accident is on the northbound carriageway and the second on the southbound.
A police spokesman said: "We are expecting there to be tailbacks and surrounding roads to be congested, so we would advise motorists to avoid the area, if possible."
A second spokesman said there are "few details at the moment" but could confirm that one of the accidents involves lorries.
Highways England has advised that there are delays on 50 minutes on the southbound carriageway to junction 33 for Galgate.
Lancashire Police have also warned motorists about improper use of the hard shoulder during the incident, saying: "Several vehicles witnessed using the hard shoulder inappropriately and they will be receiving letters through the post for intended prosecutions.
"Don't be selfish. Be patient."