The helicopter's pilot, Bjorn Nergård (52) from Ski, and Anders Rostrup Nakstad (38), a doctor on board, were both killed when the helicopter disintegrated on landing. A third member of the team has been flown to hospital for emergency treatment.
" I knew both Anders and Bjorn as professionals and as friends, and have only positive things to say about both of them," Terje Strand, head of the ambulance base in Lørenskog where the two were based, said. "They were both really trustworthy, and very skilled at their jobs."
He said Nakstad had played an important role after Anders Breivik's 2011 gun massacre on Utøya, treating the young men and women who swum from the island.
Witnesses said that the helicopter had clipped high voltage power lines as it came down to land on the road, which had been closed off by police after a truck overturned by the Sønsterud tunnel, about half an hour's drive from central Oslo. The accident happened at about 10.30am on Tuesday morning.
"Somoeone was waving the helicopter down when it looked like it hit a wire," Finn Tormod Waal, a bus driver at the scene told NRK. "The lines are blank, so it is possible that the helicopter pilot did not spot it. When it hit the wire it went straight to the ground."
Kjell Magne Tvenge, chief of staff with the Buskerud Police said that police officers had tried to warn the pilot about the difficult landing positions, but had been unable to get through across the radio.
"Police attempted to contact the pilot to notify him of the difficult landing conditions, with snow and power cables," Tvenge told NRK. "As the helicopter approached, all the rescue crews saw that it was going to be very close and were probably trying to give visual signals to the helicopter."
Tor Nørstegård, who has been tasked to find the cause of the crash for the Accident Investigation Board of Norway, said that it was a difficult place to land.
"It is a complex area that is confined between the mountains and has several high voltage power lines. It is possible to land there, but not easy."
There are at present no signs of a technical fault in the helicopter.