The incident occurred at approximately 10.40am on the A421, heading from Milton Keynes towards Junction 13 of the M1, involving six cars and a lorry. Several people were injured as a result, two of which are being treated for serious injuries.
PC Andy Ralph, said: “We believe there may have been people who had seen the incident occur and left once the police had arrived. I would urge anyone who witnessed the incident take place to call 101 and report any information they have.”
The road is currently closed in both directions as emergency services are at the scene.
Anyone with information is asked to contact the Bedfordshire Police on 101, quoting the reference Operation Ruthenium.