MOSCOW  Militants attacked a hydroelectric power plant in Russia’s restive North Caucasus region on Wednesday, killing two guards before setting off several bombs that forced the facility to be shut down, Russian investigators said.

Between three and five armed men raided the plant, a small station in the southern Russian region of Kabardino-Balkaria, around 5:30 a.m. local time, the investigators said. They said the attackers shot the two guards, then broke into the engine room of the plant, the Baksanskaya station.

“Unknown men in masks broke into the power plant, broke down a closed door, then tied up the employees,” Valery Shigenov, the plant’s director, told Russian television. Two of the employees were injured and had to be hospitalized.

The militants then set and detonated at least four bombs, which destroyed three generators, but failed to cause a breach in the dam, officials said. A fire caused by the explosions had been extinguished by midday, and no power failures were reported in the region.