The explosion on Friday triggered a fire that tore through the service station and its cafeteria on the outskirts of the regional capital, Makhachkala, said Russia’s Emergencies Ministry, adding that two children were among the dead. The fire was extinguished. Makhachkala is about 1,600 kilometres south of Moscow. Regional authorities said a criminal investigation was opened and Saturday has been declared a day of mourning in Dagestan. Last August, a massive explosion at a petrol station in Dagestan killed 35 people and injured 115 more.