The A1 remains closed in both directions near Boroughbridge between junctions 47 and 48 following a collision involving two lorries.
North Yorkshire Fire and Rescue Service are dealing with a small chemical leak from one of the lorries.
The chemical is sodium hydroxide with a product name Proxel
A 1000 litre drum on one of the vehicles sustained a small puncture, resulting in a leak of approximately 300 litres of chemical. The remaining chemical has been decanted into another drum.
Some fire crews are now leaving the scene, Harrogate are now returning to the station.
Diversions are in place at both junctions, however, drivers are asked to avoid the area and find alternatives routes if they are due to travel through the area.
Drivers are also asked not to use the hard shoulder and leave it free for emergency vehicles.
The road is expected to remain closed for some time while the vehicles are recovered and the carriageway is cleared.
One of the drivers has been taken to hospital with a hand injury.