The collision occurred on the M25 between Junction 27 (M11) clockwise towards Junction 28 (Brook Street Roundabout, Brentwood) just before 4.40pm
Five cars and a van were involved. It is believed a small green Peugeot car may also have been involved but failed to stop at the scene.
An ambulance was also in attendance.
A 22-year-old man was taken to hospital with a suspected spinal injury and a second male treated at the scene.
The M25 was closed for a considerable time causing major disruption to the network whilst police investigated.
Police are asking that anyone who travelled the route to check their dash cam for any footage of the collision and to preserve it for police.
Call 101, quoting incident 768 of 8 December, if you saw what happened or can help police with any dash cam footage. You can use the ‘Live Chat’ button to speak to an online operator between 7am-11pm or you can submit a report online at https://www.essex.police.uk/.