The accident, involving a grey Citroen C3 Executive and a blue Vauxhall Astra, happened shortly before 1pm at Kingstanding, near Crowborough, where the B2026 meets the B2188.
An 81-year-old man driving the Citroen, and his 76-year-old wife, who was the front seat passenger, were taken to the Royal Sussex County Hospital, Brighton. Both were detained with serious, possibly life-threatening injuries.
A 29-year-old Eastbourne man driving the Astra was taken to the Kent and Sussex Hospital, Pembury, where he was treated for a broken arm.
Roads in the area were closed to through traffic while the incident was dealt with.
The Kent, Surrey and Sussex Air Ambulance attended, but all the casualties were taken to hospital by land ambulance.
Anyone who saw the collision or who may have other information is asked to email firstname.lastname@example.org or call 101, quoting Operation Quake.
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