Hertfordshire Police, the ambulance service and the fire service are at the scene
Officers were called at around 9am this morning (Monday) to reports of a collision at the Park Street roundabout on the A414 North Orbital Road, St Albans.
Several vehicles were involved in the collision, including a LGV (large goods vehicle). Two people were injured.
The A414 is closed from M1 Junction 8 (Hemel Hempstead) to the Park Street roundabout (Watling Street) to allow emergency services access.
Police are advising drivers to avoid the area.
Hertfordshire Fire and Rescue Service and the East of England Ambulance Service are also at the scene.
The fire service sent four engines and the Rescue Support Unit from St Albans.
A spokesman for Hertfordshire Fire and Rescue said: "Road traffic collision on roadway involving two vehicles and one LGV. Lukas cutting equipment in use, two casualties placed in the care of the ambulance service.
"Crews are currently still on the scene."