Medics were called to Alconbury at about 10.30am after reports of a man, believed to be in his 50s, who was unconscious. An East of England Ambulance spokesman said: CPR had been started prior to the arrival of an ambulance crew, who arrived within six minutes of the 999 call being made. Due to the severity of the casualtys condition, we decided it was necessary to request the critical care paramedics and the air ambulance flew to the scene. Fortunately, the medics managed to get a return of spontaneous circulation, which means they were able get the mans heart beating again in a normal rhythm. The critical care paramedics then anaesthetised the casualty at the scene in order to help stabilise him, and he was flown to Papworth Hospital for emergency treatment. On arrival at hospital his condition was believed to be life-threatening.