The air ambulance landed at what was thought to be a serious crash on the A11 on Thursday night where people had to be cut free from vehicles.
Norfolk Police tweeted at 9pm to say the A11 Norwich-bound at Ketteringham had been closed due to a crash.
Two vehicles were involved and four fire engines rushed to the scene, between the A1075 and the A47.
Crews used hydraulic rescue equipment to free people who were trapped and the air ambulance was also called.
Tailbacks were reported on the busy route and the road was not expected to reopen until 2am on Friday according to Highways England.
One eyewitness said they saw police and emergency services working around the side of the road, and into the bank.
Police were diverting traffic and advised choosing alternative routes.
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