The westbound A14 between Newmarket and Cambridge will be closed until this evening after a major fuel spill.
Two lorries collided on the road close to junction 35 at Stow-cum-Quay at 6.10am.
Highways England has been forced to close the road between the A11 (junction 36) and junction 34 as up to 100m of carriageway needs to be resurfaced following a fuel spill.
Motorists are being warned of severe delays in the area.
Traffic is being diverted via the A11, A505 and M11, re-joing the A14 at junction 31.
Highways England says the carriageway is likely to remain closed until later this evening.
Repairs will begin out as soon as debris has been cleared off the road and recovery of the lorries completed.
The agency added that the A14 will fully reopen as soon as it is safe to do so.
Two people were taken to Addenbrookes Hospital, Cambridge, with minor injuries following the crash.
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