Authorities said on Sunday their investigation showed a 29-year-old Briton shot the polar bear that killed one of the members of an expedition he was leading in the Norwegian Arctic . \"A 29-year-old (team) leader shot the bear. The man was already injured by the polar bear when he fired the shot that killed it,\" the office of the Svalbard governor said in a statement. It explained coming to the conclusion after local police interviewed three of the four Britons -- all males aged 16, 17, 27 and 29 -- who were injured in the attack. Eight other campers, who escaped Friday\'s attack unhurt, had been interviewed Saturday. Early Friday, a 250-kilo (550-pound) male polar bear attacked the camp site of 13 young Britons who were on a five-week trip on the Svalbard archipelago organised by the London-based British Schools Exploring Society. Horatio Chapple, a 17-year-old who dreamed of becoming a doctor, was mauled to death before the bear was shot. The governor\'s office said it \"is now clear that the bear had entered the tent camp at Von Postbreen glacier unnoticed\" because trip wires installed around the camp alert to the presence of polar bears did not detonate. Local authorities \"have now examined the bear ... It had a very thin fat layer and little content in its stomach,\" it added. The University Hospital of North Norway, where the four men were treated for head injuries -- serious for two of the patients -- said in a statement two patients were flown home to Britain in ambulance planes Saturday. The two others will be sent back, also in ambulance planes, on Monday, it said. According to Norway\'s TV2, Friday\'s attack was the first deadly polar bear attack in Svalbard since 1995. Chapple\'s death brings to five the number of people killed on the archipelago since 1973, when polar bears became a protected species, it reported.