An explosion of unestablished device took place on stairwell of 5-storied apartment house in Leninsky district of Makhachkala, informed in law machinery organs of Dagestan. "An explosion occurred at 03:20 by Moscow time on third floor of 5-storied house near flat of pensioner. There are no victims. The entry door has been damaged insufficiently", - informed representative of law machinery. By his words, circumstances of accident are investigated.