An accident closed the A1 near Borehamwood this afternoon.
Emergency services were on the scene of a collision on the southbound carriageway just past the Rowley Lane exit.
At least two vehicles were involved and several ambulances, fire engines and police vehicles were present.
The A1 has now been reopened according to Traffic England, but 15 minutes of residual delays are to be expected.
Traffic officers were also on scene to direct motorists off the A1 in Borehamwood.
Police received a report at 12.47pm today of a collision involving a number of vehicles on the South Barnet A1 Bypass
At least four people were injured, but none appear to be in mortal danger at this time.
Two people were trapped inside their cars and firefighters were present with cutting equipment.
At 1.40pm queues on the southbound A1 returned to Galley Lane, with all motorists being taken to Rowley Lane.
There was no traffic stuck between the closure and the collision, as it happened just after the junction.
Police have closed access to the southbound A1 for people heading there from the roundabout near the Doubletree Hilton Borehamwood hotel.
This meant that there was also no access on Rowley Lane towards Barnet for drivers coming from Borehamwood.
Northbound A1 carriageway is clear.
There was a collision involving multiple vehicles on the southbound carriageway of the A1 #Barnet Bypass. Emergency services are currently on the scene, but motorists are advised to avoid the area as congestion is severe. Thank you for your patience. pic.twitter.com/KZdMVp4ijL
—Herts Police (@HertsPolice) June 25, 2022
Southbound delays will likely take a while to clear up