But long before officials concluded that terrorism was the cause, the residents of 19 Guryanovo Street in Moscow sensed that evil, not carelessness, was behind the blast that destroyed their apartment block as they slept.
The survivors could remember only the horror, but those who escaped unscathed gave cooler accounts. It could scarcely be a coincidence, said one teenager, that the explosion rocked the building on the stroke of midnight. He was sure of that because he had been listening to the Russian national anthem, played on the radio to mark closedown.
Other residents said they had smelt no gas, rather an acrid stench like sulphur. One eyewitness claimed to have seen four men speeding away in a Ford Taurus car, minutes before the blast occurred.
Only on Friday did forensic experts from the Federal Security Service confirm that a massive bomb had been planted. A claim of responsibility from a man with a Caucasian accent suggested a link to the troubled south, where federal forces are fighting to expel Chechen militants from Dagestan. Yesterday, with the death toll over 90, the authorities confirmed they had arrested two suspects, but refused to give further details.
Tomorrow a day of national mourning has been declared among the long- suffering Russian people, who have been tightening their belts in vain for the past decade while criminals have hijacked their market reforms. Allegations of corruption have gone all the way to the Kremlin and President Boris Yeltsin himself. Parliamentary and presidential elections are approaching, yet there are doubts that voters will actually reach the polling booths - some predict the elections will be cancelled - or that if they do, they will be given a meaningful choice.
And now, despite the attempts of the army to play down the conflict, it is clear Russia is again involved in a full-scale war in the Caucasus. Just as the troubles in Northern Ireland spilled over into English cities, so this war is coming to Moscow.
After the apartment block bomb in Pechatniki, a working class suburb, and another blast on 31 August, Muscovites are afraid to go out, and afraid to stay at home. Only the thousands of innocent Caucasian immigrants in Moscow - never much loved, always easy scapegoats - will be more scared.
With the benefit of hindsight, many Russians realise that it was a tragic mistake to carpet-bomb the city of Grozny during the 1994-1996 war with Chechnya, so that a wasteland yawned, fertile soil only for anarchy. Islamic fundamentalist warlords now hold the real power there. Funded, according to the Russian security services, by the radical Osama bin Laden, they are trying to destabilise neighbouring regions where the majority of people appear genuinely to want to remain within the Russian Federation - for the time being at least.
In Dagestan, the army is trying to learn from its mistakes, taking care, for example, to avoid civilian casualties. But President Yeltsin's instinct remains to lash out and crush.
As for ordinary Russians, they were still in shock. The victims of Guryanovo Street were poor, but at least they had a shabby roof over their heads. Now even that has gone.