UCKFIELD High Street was closed to traffic on Monday afternoon as emergency services dealt with a four-car collision.
Police received several calls around 2.35pm to the scene close to the Post Office. A Vauxhall Vectra and a Peugeot were among the vehicles involved.
The Air Ambulance also attended.
An East Sussex Fire and Rescue spokesman said firecrews had to use hydraulic equipment to free one person who was trapped. He was taken to the Royal Sussex County Hospital with chest pain and possible chest injury. But it is believed there were no other serious injuries.
Firecrews stood down at 3.47pm.
Police would like to hear from anyone who saw the incident.
They should ring: 0845 60 70 999 quoting serial number: 995/08/08