BBC, July 21 -- Armed militants have stormed a hydroelectric power station in Russia's volatile North Caucasus region, killing two guards and detonating four bombs.
TV footage showed fires raging at the plant, in the mainly Muslim republic of Kabardino-Balkaria republic.
Officials said the fires were now under control, and that electricity supplies had not been affected.
Analysts say it appears to be an escalation of Islamist insurgent attacks on Russian economic targets.
"This shows the scourge of terrorism is not only not subsiding, but expanding geographically," said Gennady Gudkov, deputy head of the security committee of Russia's parliament, according to the Reuters news agency.
President Dmitry Medvedev said that security had been stepped up.
"Spoke to head of FSB [security service] and president of Kabardino-Balkaria. Security at strategic sites tightened after today's explosions," he said in a message on the social-networking website Twitter, which limits messages to 140 characters.
Kabardino-Balkaria has seen less militant violence than the other semi-autonomous republics in the region: Chechnya, Dagestan and Ingushetia.
The most serious attack in Kabardino-Balkaria came in October 2005 when dozens of men stormed the regional capital Nalchik. The Russian government said 136 people were killed, including 91 militants.
'No disaster threat'
State-owned firm RusHydro, which runs the power station, said in a statement on its website that explosions had hit the plant at 0525 local time (0125 GMT) on Wednesday.
The attackers detonated four explosive devices in the 25-megawatt plant on the Baksan river, but a fifth failed to go off.
Investigators said two explosions shook the plant's turbine room and another two hit the transformer vault.
According to police spokesman Adlan Kakakuyev, two cars carrying half a dozen assailants had attacked the plant, shooting two guards and wounding three other people.
The attackers reportedly seized two Kalashnikov assault rifles from the dead guards.
The same group are believed to have earlier opened fire on a police station in the town of Baksan.
Officials said the flow of water from the dam, on the Baksan river, had been stopped to prevent any flooding downriver.
Electricity supplies had not been disrupted because power had been rerouted from elsewhere, the authorities said.
Regional officials said there was no further danger of a "technical accident or disaster" at the plant, which was built in the 1930s.
According to Russia's Ria-Novosti news agency, Russian Prime Minister Vladimir Putin has put Deputy Prime Minister Igor Sechin in charge of repairing the damaged power station.
- Militants hit Russia power plant, killing two guards - BBC
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