Several witnesses described seeing a powerful explosion
Rescue workers said Friday they had seen no sign of survivors from a helicopter that crashed in western Norway with 13 people on board, but said the search was continuing.
"They are searching in the hope of finding survivors. So far we have not seen any sign of survivors," Sola rescue centre spokesman Anders Bang Andersen told reporters.
The helicopter crashed off the western coast of Norwayon Friday, police said, with media reporting that 13 to 17 people were on board.
Several witnesses described seeing a powerful explosion and people were seen in the sea, television station TV2 reported, adding that some people had been rescued.
"Emergency services en route to a zone near Turoy after reports of a helicopter crash," Norwegian police wrote on Twitter, referring to an island off the western town of Bergen.
First reports indicated the helicopter was transporting workers to an offshore oil field in the North Sea.
Various media reports put the number of people on board at between 13 and 17.
Live footage showed leisure boats rushing toward the scene, where thick black smoke was billowing into the sky.