At least four people have been killed in an explosion at a gas station in Russia’s southern region of Chechnya, officials have said. The explosion of a gas tank triggered a fire at the service station in the regional capital, Grozny, said Russia’s Emergencies Ministry. The ministry said that two children were among the dead. Local media said seven fire engines and 35 firefighters were deployed to tackle the blaze which has since been extinguished. Grozny is about 1,500 kilometres south of the capital Moscow. Regional authorities said the cause of the explosion is unknown but that a criminal in…