Two people in their late teens died in a collision involving two cars, Suffolk Police said.
Officers were first called by the ambulance service to Debenham Road near Little Stonham at 10:15 BST.
Fire crews and the air ambulance were also called to the incident that involved a red Peugeot 107 and a silver Volkswagen Passat.
Police said a male passenger in the Peugeot died at the scene. The female driver was taken to Addenbrooke's Hospital in Cambridge by land ambulance, but has since died as a result of her injuries.
The occupants of the Passat suffered minor injuries, the police spokesperson added.
The road was expected to reopen later in the evening.
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