Two people have been killed in today’s accident on the A421 and four more are in hospital tonight.
The bypass was closed this afternoon after a multi-vehicle accident involving four cars and two lorries at around 2.10pm on the eastbound carriageway close to the A6 junction.
Two air ambulances were called to the scene but one person was pronounced dead at the crash site and another later died at Bedford Hospital.
Four other motorists were taken to the hospital where their conditions are described as not critical.
A full collision investigation has been launched by Beds Police and both the east and westbound carriageways are expected to remain closed for most of the night between the Marsh Leys roundabout and the junction with the A600.
PC Andy Ralph of the Beds, Cambs and Herts forensic collision investigation unit is appealing for anyone who witnessed the incident to come forward. Among those who may be of particular help are drivers with dashboard cameras.
One man has been arrested on suspicion of causing death by dangerous driving and is currently being interviewed by officers.
Motorists are being urged to avoid the area while investigations continue.
Anyone with information about the accident can contact police, in confidence on 101 or via Crimestoppers, anonymously, on 0800 555 111.