Part of the M1 has been closed in both directions as a result of a two-car crash.
Police and ambulance services are currently at the scene following the collision between a silver Citroen Saxo and a silver Vauxhall Zafira about 1.15pm.
The stretch of road between J7 and J6a has been closed in both directions.
The female driver of one of the cars is being treated for head injuries on the side of the road, but she is conscious and breathing.
Attempts are being made to free the other driver who is currently trapped in her vehicle.
One of the cars is believed to be smoking, and severe traffic delays are being reported up to J8 at Hemel Hempstead.
East of England Ambulance Service spokesman Gary Sanderson said: “At present we are treating two casualties, one of which is trapped in a vehicle.
“We have a rapid response doctor en route to the incident from London to assist in the extrication of the trapped casualty.”
