The town, between Volgograd and Rostov on Don, 800 miles south of Moscow, grew up in the Stalin era around a hydroelectric plant. A nuclear power station is being built in the area but neither the old dam nor the unfinished station was damaged by the blast on a housing estate.
The explosion carried many of the hallmarks of four bombs in Moscow and in Buynaksk, Dagestan, which have killed 275 this month. An organisation calling itself the Dagestan Liberation Army (DLA) has claimed responsibility for those attacks.
Police in Volgodonsk said the nine-storey block had been checked before the blast as part of national security measures named "Operation Whirlwind".
Russians have been told to look out for strangers or unfamiliar vehicles, but the bomb was planted in a truck the residents were used to seeing. Presumably it was stolen from the yard, they said.
The fact that the bomb was in a lorry and not placed inside the building, as in two cases in Moscow, explained why more people were injured than killed, whereas in the capital there were high death tolls - 92 in one bombing last week and 118 in the other on Monday.
Still, the spokesman for the Federal Security Service saw the latest attack as "another link in the same chain". The DLA, which claimed responsibility for the earlier bombs to Itar-Tass news agency on Wednesday, said it was avenging the deaths of Muslim women and children in Russian air raids over Dagestan. "This is a warning. We will answer death for death," it said.
The DLA was unknown before August, when militants from the breakaway region of Chechnya invaded Dagestan, joining a tiny group of adherents to the fundamentalist Wahhabite sect and declaring a Jihad - a holy war - for Dagestan's independence.
The Russian army's success on the battlefield in late August may have turned the militants to terrorism. Federal forces are again claiming "victory" in the Novolaksk district of Dagestan, but celebration is probably premature; news agencies say gunmen are again massing just inside Chechnya, probably for a new incursion into Dagestan.
The Russian Prime Minister, Vladimir Putin, has called for a blockade of Chechnya, which has descended into anarchy since the 1994-96 war for freedom from Russia.
Mr Putin talked tough yesterday after the latest bomb. "For too long," he told his cabinet, "we have closed our eyes to the fact that we are being made second-class citizens in our own country. We have spoken to the bandits in the language of law while they have used the language of violence. I urge you not to dither or panic but to grit your teeth and act decisively."
Despite suspicions that President Boris Yeltsin might be seeking a pretext to cancel elections, neither the Prime Minister nor any other politician has suggested that a state of emergency is necessary. The authorities are relying on a mix of heightened activity among the special services and alertness on the part of ordinary citizens.
"Operation Whirlwind" has already borne some fruit in Moscow; 27 people have been detained in connection with the bombings, although the authorities admit they are not the chief perpetrators. Caches of explosives have been found and new blasts prevented.
But, if Major Vyacheslav Izmailov, an army officer, is correct, more cities could be threatened. His sources say three groups of bombers fanned out from Dagestan to Moscow, Rostov on Don and St Petersburg. The capital has been hit, as has a town in the Rostov region. St Petersburg should be worried.Reuse content