Makhachkala, Dagestan (CNN) -- At least four people are dead and 44 are injured after two bombs exploded Monday in Russia's volatile North Caucasus region, the Ministry of Health's website says. Thirty-one of the injured were hospitalized, it says. The incident -- which occurred in Makhachkala, capital of the semi-autonomous republic of Dagestan -- also caused significant damage. Security officials say they believe law enforcement officers may have been the target because the explosion occurred outside a local marshal's building. One car bomb was discovered by a police patrol, who called in a unit to defuse it. Before that could be done, the bomb went off, but the explosion was minor, security officials said. Then, as a crowd of people gathered, a second, more powerful device detonated, causing the casualties.
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Two bombs exploded outside a local marshal's building, the Ministry of Health says
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The first explosion was minor; the second went off as a crowd gathered
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The Boston Marathon bombing suspects hail from the North Caucasus
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In Moscow, security forces say a terror plot is foiled
Russia has been on edge over militant activity and its security forces announced on Monday that they foiled a terror attack planned for @placeholder.