Explosion in Istanbul after a helicopter crashes into a tower

A helicopter has crashed on a motorway in the outskirts of Istanbul killing seven 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.
Istanbul mayor Kadir Topbas said: 'Seven people were killed in the accident. I would like to send my condolences to the loved ones and to the companies they belonged to', according to Hurriyet Daily.
No one on the ground appeared to have been injured after the crash, the Buyukcekmece district mayor Hasan Akgun said.
The Russian victims have been named locally as Aleksandır Vanin, Igor Kochergin, Luidmina Churova and Elena Badraga, according to Hurriyet.
They are reported to have been travelling with Salim Özen, 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 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