A helicopter of the sanitary aviation heading for Salekhard has taken onboard two persons, injured in an explosion at the Malyginskoye gas condensate field in the Yamal-Nenets Autonomous Area in northwest Siberia, press service of the local healthcare authorities told TASS on Saturday. "One of the injured had undergone a surgery at night, and the second one has received necessary assistance, but both of them remain in poor conditions," the press service said. "They were prepared for transportation, and at about 9:30 local time the helicopter left for Salekhard, where they will be taken to the district hospital." Press service of the local governor reported six people killed or injured in the explosion. The information on the victims is not final yet: some sources claim three and others claim four dead. The regional sanitary aviation told TASS about four dead. The press service of the local emergencies department said the blast had occurred at around 3.00 p.m. Moscow time in a trailer during the work on preparing explosive charges. The works were carried out by a subcontractor, Kostroma Geofisika. The gas field belongs to Gazprom. The press service said an emergency response team had been set up to deal with the consequences. A pre-investigation check was underway. The field is located at a distance of 130 kilometres from the nearest settlement and at a distance of 600 kilometres from the Yamal capital city Salekhard," the spokesman said.