A senior local government official in Russia's turbulent North Caucasus region was killed in an explosion on Friday, local police said. The blast went off as Zagir Arukhov, information and nationalities minister in Dagestan, a semi-autonomous republic, entered the stairway of his apartment block in the regional capital Makhachkala, police said.Dozens of senior figures in Dagestan's government have been assassinated and some Russian media have dubbed Makhachkala "explosion city." Arukhov's predecessor in the post was also killed in an explosion. Analysts say business disputes and clan rivalries are, for the most part, to blame for the violence in Dagestan. However, the fighting in Chechnya has also spilled over into nearby provinces, including Dagestan.