At least two police officers were wounded as an explosion rocked the capital of Russia\'s volatile North Caucasus republic of Dagestan in the early hours of Friday, a police source said. The explosion occurred in Makhachkala\'s central Yaragsky Street soon after midnight (20:00 GMT), the source said. According to preliminary data, an explosive devise hidden in a bush went off when a police patrol car stopped nearby.A Dagestani Interior Ministry spokesman confirmed the report, adding that the two police officers had been admitted to hospital with light injuries. Russia has been battling a low-level Islamist insurgency in several North Caucasus republics. Dagestan, along with Ingushetia, has seen the brunt of the fighting in recent years.