A Norwegian investigator says the oil-rig helicopter that crashed in Norway, killing 13 people, gave no mayday call or indicated it was in trouble.

Kare Halvorsen from Norway's Accident Investigation Board says Monday their probe has shown no such evidence, but he declined to speculate on the cause of the accident.

The victims — 11 Norwegians, one Briton and one Italian — were aboard the Airbus EC-225 helicopter flying in from an offshore rig in the North Sea when it crashed Friday on the tiny island of Turoey outside the western city of Bergen.

Norwegian police on Monday released the names of seven victims. Police spokeswoman Gry Benedicte Halseth said the families of the remaining six victims did not want to their names released.