Three people were left seriously injured and two girls aged four suffered minor injuries after a two-vehicle crash.
Emergency services were called to the crash in the A1071 outside Hadleigh at about 4.30pm on Wednesday.
It was reported to police that two cars - a black Peugeot 207 and a red Renault Clio - had left the road.
The driver and sole occupant of the Peugeot, a man aged in his 20s, sustained serious and potentially life-changing, injuries.
The driver of the Renault, a man aged in his 70s, sustained serious and potentially life-changing injuries.
The front passenger, a woman aged in her 30s, also sustained serious and potentially life-changing injuries.
The rear passengers, two four-year-old girls, sustained minor injuries.
Everyone involved was taken to hospital for treatment.
The road was closed in both directions to allow for recovery of the vehicles and an investigation into the circumstances of the incident.
It reopened at about 11.20pm.
Police are appealing for any witnesses to the collision, any motorists with dashcam footage who were driving in the area around the time of the incident and anybody who witnessed the manner of driving of the vehicles involved.
Anyone with information is asked to contact the Roads and Armed Policing Team at Suffolk police, quoting CAD 212 of August 2.
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