A teenager was stabbed in the chest while out at a Bank Holiday market.
The 17-year-old was knifed in the abdomen at Bourn Airfield Market in Cambourne, Cambridgeshire.
A police helicopter was spotted flying nearby while an air ambulance landed in a field behind the stalls.
The market, which takes place in the village every Bank Holiday, attracts around 20,000 customers each market day.
It is held at the historic World War II airfield near Cambourne village and plays host to more than 400 different stalls.
It is not currently known what condition the victim is in.
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A long section of the market has been taped off by the police as they investigate the incident.
Most of the market is still open however.
Statistics released by Cambridgeshire Police suggest Cambourne is a comparatively safe area.
In the broader Cambourne area - which covers large, rural parts of the county - there were just 20 weapons possession offences recorded last year.
