Militants broke into a hydroelectric power plant in Russia's North Caucasus region, killing two people and wounding another two.
State-run power group RusHydro said the attack happened at the Baksanskaya hydroelectric power plant.
The company said the incident was likely a ‘terror act.’
Officials, including an officer with Russia's security service FSB who spoke on condition of anonymity, said unknown assailants burst onto the premises of the station and killed two guards.
They tied up staff employees at the power plant. ‘Some time later an explosion took place in the engine room,’ regional official Gennady Vykhristyuk said in televised remarks.
The explosion partially damaged the plant and set it on fire.
Authorities however had managed to stop the flow of water and put out the fire, said Mr Vykhristyuk.
‘There is no danger of a technological accident or catastrophe,’ he added. ‘The power plant's staff are alive and well.’ He did not give further details on how the staff who had been tied up were freed.
The FSB official said law enforcement officials, including sappers, were now working at the scene. It was not immediately clear how many blasts there had been at the plant, he said.
Built in the 1930s, the power plant is located on the Baksan river in Kabardino-Balkaria, part of the North Caucasus region where Russian authorities are battling a Muslim insurgency.
President Medvedev has said the unrest in the Caucasus is Russia's most serious domestic problem.
Earlier this month Prime Minister Vladimir Putin introduced a new economic drive to end the unrest in the Caucasus in an ambitious drive to bring prosperity to the region.
