Police officers wearing gas masks patrol the streets of the village of Kara-Zhygach during an explosion on the banks of Naryn river, some 400 km (249 miles) south from the capital Bishkek December 22, 2009. Kyrgyzstan began to dam a key Central Asian river on Tuesday to build a new hydroelectric power plant, a project criticised by neighbouring nations who fear it will disrupt water supplies. Picture taken December 22, 2009. REUTERS/Vladimir Pirogov (KYRGYZSTAN - Tags: ENERGY POLITICS)