Police closed the M1 northbound and southbound between J36 and J37 in Barnsley after the crash at around 1.45pm.
The air ambulance has been called to the incident and landed on the M1 near Junction 36.
A Highways England spokesman said: "M1 southbound is now flowing again. The air ambulance has landed on the northbound carriageway so the M1 is now closed northbound J36 to J37. Diversion details to follow.
"If you are caught in the 'trapped' traffic, we are making preparations to release you passed the scene as soon as the Air Ambulance has departed. Please bear with us and stay with your vehicle."
UPDATE: The road has now reopened as of 3.30pm