MOSCOW, February 5. /TASS/. Pilot error, bad weather conditions and a technical failure are among the probable causes for a Mi-8 helicopter that crashed in northwest Russia’s Karelia late on Sunday, an emergency official told TASS.

"So far, there is no priority version. Bad weather, pilot error and a mechanical failure are being considered as probable causes. According to available data, the crew had not reported any mechanical malfunctions [on the helicopter]," the official said.

The Russian Emergencies Ministry flight had undergone a routine technical inspection before flying off from Petrozavodsk, he added.

The helicopter with three crewmembers on board has went missing over Lake Onega in Karelia on Sunday evening.