Officials in the town of Znamenskoye, an area considered to be a largely stable part of Chechnya near its border with the Stavropol region, say the death toll from the suicide attack is expected to rise.
The violence is the biggest flare-up since Russia held a constitutional referendum in March in an effort to find a peaceful solution to three and a half years of fighting between Russian forces and Chechen rebels seeking complete independence from Moscow.
Russian President Vladimir Putin said the attackers were trying to undermine the stability created by a loose political federation with Russia.
“All similar actions are aimed at only one thing: to stop the process of settlement in Chechnya, to stop the process of a political settlement,” Mr. Putin said in a televised address to his cabinet. “We cannot allow anything like that, and we shall not allow it.”
The truck pulled up to a checkpoint outside the government compound at about 10 a.m. local time, and exploded about 100 feet from a protective concrete wall, according to Nikolai Patrushev, the director of the Federal Security Service, or F.S.B., the successor to the K.G.B. that now leads the campaign against Chechen separatists.
The explosion, estimated to be the equivalent of a ton of TNT, left a crater more than 30 feet wide and 6 feet deep and damaged the headquarters of the regional government as well as offices of the Interior Ministry and the F.S.B.
The attack is the latest in a series of deadly violence in the region since the collapse of the Soviet Union in the early 1990s. Last December, a similar truck bomb killed more than 70 people outside the headquarters of Chechnya’s pro-Moscow administration in the capital, Grozny.
A tense security situation continues to dog Chechnya, despite efforts by Moscow to reduce the number of federal forces patrolling the war-torn region and encourage thousands of Chechens who have fled the country to return to their homeland.
Last Friday, a bomb that had been planted near a stadium in Grozny exploded, wounding three policemen as citizens gathered nearby for a parade marking the Russian Victory Day holiday that commemorates the defeat of Nazi Germany.