There are delays on the M25 near London Colney after four cars collided at lunchtime today.
The incident occurred just before 12.30pm on the clockwise exit slip-road toward the South Mimms Services between Junctions 22 for London Colney and 23 for the A1(M).
Paramedics from two ambulances attended the scene and treated two drivers for neck pain and suspected whiplash before they were taken to Watford General Hospital at 2.14pm.
The vehicles involved were a silver Peugeot 206, a blue Renault Clio, a grey Fiat 500 and a blue Peugeot 307, which police organised for a recovery vehicle to take away from the scene.
The Highways Agency reported delays of ten minutes to the clockwise carriageway, which were expected to last until 3.30pm.