The A10 is closed between Royston and Reed after a serious crash, with a man trapped inside one of the two cars involved.
Police, speaking to the Crow at 10am, said the crash had happened at 8.45am and that a man was still trapped inside one of the vehicles.
A force spokeswoman said the cars involved were a silver Vauxhall Corsa and a grey Hyundai.
Herts County Council’s Highways department has indicated that the road is likely to be closed for some time, and the fire and rescue service has described the crash as “serious”.
Both have urged motorists on Twitter to avoid the area.
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