The A134 south of Bury St Edmunds has reopened after an earlier collision between a lorry and two cars forced the road to close.
Officers from Suffolk police shut the road near Bradfield Combust and Great Whelnetham, a few miles south of the town, in both directions after being called out at around 10.45am on Wednesday.
Three Suffolk Fire and Rescue Service crews, from Bury St Edmunds and Long Melford stations, were dispatched and an air ambulance was called.
The fire service advised motorists to avoid the area if possible.
A spokesman for Suffolk police confirmed four people had been injured in the incident and were being treated for their injuries.
However, their conditions are not known at this time.
Suffolk police said the vehicles were recovered shortly after 2pm and the road has since reopened.
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