Police closed the north bound carriageway between junction 42 at Lofthouse and junction 43 at Belle Isle just after 2pm.
Two cars were involved in the incident.
A spokeswoman for West Yorkshire Police said: “We have received a report that one person is trapped. Firefighters and paramedics are on the scene.”
All four lanes of the motorway are currently closed and the south bound carriageway is due to be closed to allow the air ambulance to land.