Motorists face delays of up to 20 minutes on the Southbound carriageway this afternoon, with queues from Hampole back to Knottingley.
Several miles of traffic have also been reported on the northbound carriageway on approach to the incident.
It is believed the traffic is the result of an earlier accident.
The road has been closed at the scene of the incident, and Highways England said that there was no entry to the A1 at the junction with the M62 at Ferrybridge.
In a tweet, they said: "#A1M southbound J41 #M62 J32A #Holmfield to J38 #Redhouse. Road closed due to serious traffic collision.
"Our #TrafficOfficers are on scene with @WYP_RPU dealing. No entry to #A1 south from #M62 westbound at J33 #FerryBridge. We will update."