French oil company Total has confirmed the death of its chairman and CEO, Christophe de Margerie, in a crash between his private plane and a snowplow at Moscow international airport.Three members of the plane's crew were also found dead at the scene of the accident.
Russian officials said they had already established that the snowplow driver was drunk but would also consider other possible causes such as pilot and air traffic control error.
"The thoughts of the management and employees of the group go out to Christophe de Margerie's wife, children and loved ones as well as to the families of the three other victims," Total said in a statement.
The Kremlin said that President Vladimir Putin had sent a telegram to his French counterpart, Francois Hollande, to express his condolences.
In the message, Putin praised de Margerie for his role in laying the foundation of "long time fruitful cooperation between France and Russia in the energy sector."
Total is a major shareholder in Novatek, Russia's largest independent natural gas producer.
De Margerie attended Putin's annual economic showcase in St. Petersburg in May, ignoring calls for a boycott over the crisis in Ukraine.
But the shooting down of a Malaysian airliner over eastern Ukraine in July prompted Total to suspend buying more shares in Novatek, with which it is planning to develop a massive liquified natural gas reserve in Siberia.
De Margerie joined Total right after finishing university in 1974. He has held several positions with the company, including a job leading its Middle East operations. He was named CEO in 2007, and appointed Chairman in 2010.