A helicopter has crashed on a motorway in the outskirts of Istanbul killing at least five people. It is understood the Sikorsky S-76 chopper was flying in dense fog when it hit a television tower which caused it to plunge into the road. There were seven people on board - an executive of the Turkish Eczabicasi group and four Russians, including the firm's Russian operations chief, plus two pilots, the company's chairman said. The Russian victims have been named locally as Aleksandir Vanin, Igor Kochergin, Luidmina Churova and Elena Badraga, according to Hurriyet. They are reported to have been travelling with Salim Ozen, CEO of Vitra Russia, a company who produce building materials. Governor Vasip Sahin said the helicopter crashed in Istanbul's Buyukcekmece district after taking off from Itsanbul's Ataturk Airport, adding that the cause of the crash is under investigation. It appears that the helicopter crashed into the Endem TV Tower, which is in the district. The chopper took off at 11.16am and crashed five minutes later, according to Dogan News Agency. Witness Fikret Karatekin, a taxi driver, told CNN-Turk television by telephone that the helicopter slammed into the tower before crashing on the highway. 'It hit the tower and crashed by spinning,' he said, adding that the highway had been closed down. The helicopter broke into piece that were scattered on the highway as well as a green area on the side of the road. Video footage from the site showed thick black smoke rising from the highway. The helicopter broke into pieces that were scattered on the highway as well as a green area on the side of the road. Video footage from the site showed thick black smoke rising from the highway. The helicopter belonged to the Eczacibasi group of companies, who also own Vitra Russia.