A bomb left in a bag exploded near a shopping mall in the capital of Russia's turbulent Dagestan Republic on Wednesday, killing two teenagers, the internal ministry said.
Mainly Muslim Dagestan, in recent years the home of the parents of the two suspects in the Boston Marathon bombing, has been affected by an Islamist insurgency for over a decade since a war in adjacent Chechnya, where Russian federal security forces forced Islamist separatists from power.
"Two teenagers were killed and two men are in a hospital in a serious but stable condition," a spokesman for the Russian Interior Ministry in Moscow said.
The explosion occurred in the Dagestan capital Makhachkala after a plastic bag containing a makeshift device was placed near a building materials shop and detonated minutes later, the state Anti-Terrorism Committee (NAK) said in a statement.
The Committee blamed the attack on "illegal armed groups", making no mention of Islamist rebels.
Ethnic Chechen Tamerlan Tsarnaev, the Boston Marathon bombing suspect who was killed during a shootout with police last month, spent several months in Dagestan in 2012 and investigators are trying to determine whether he had contact with Islamist radicals during his stay.
Three people were killed and 264 injured by twin bombs left near the finishing line of the marathon race on April 15. Tamerlan Tsarnaev died later in a shootout with U.S. police while younger brother Dzhokhar was arrested and charged with crimes that carry the possibility of the death penalty.