At least five people were killed and 35 wounded Sunday when a suicide bomber attacked troops at a firing range in Russia's southern republic of Dagestan, sources in official security agencies said.
The bomber detonated a car packed with explosives at the firing range outside the town of Buynaksk, about 30 miles west of the local capital, Makhachkala, said the sources, who declined to be identified.
The suicide bomber rammed the gates of the 136th motorized rifle brigade, said RIA Novosti news agency.
The unit's guard blocked the car, preventing a larger death toll, RIA said, citing anonymous sources.
A second explosion rocked the town as investigators were heading to the site, RIA said. However, the second bomb exploded after a police car responding to the car bomb passed. No on was killed or injured in the second blast, RIA said.
Servicemen in Buynaksk have repeatedly come under terrorist attacks.
A car bomb wounded a senior Russian official and killed his driver Saturday.
Bekmurza Bekmurzayev, the regional minister in charge of national policy, religious and foreign affairs, was taken to hospital along with two bodyguards, also injured in the attack, Russia's investigative committee said in a statement.
In July, servicemen of the 136th motorized rifle brigade came under fire. Three people were killed, RIA said.
In 2007, an explosive device planted on the roadside detonated when the brigade's servicemen were returning from military exercises. Two were killed and two injured, the agency said.
There has been a surge in violence over the past two years in the mainly Muslim North Caucasus, especially in Dagestan, Chechnya and Ingushetia. Russia fought two wars against Chechen separatists since the 1991 fall of the Soviet Union.
The Kremlin has pledged to wage "a ruthless fight" against militant groups but also has acknowledged a need to tackle unemployment, organized crime, clan rivalry and corruption as causes of the ongoing violence in the region, RIA said.