MOSCOW - The Moscow Metro was packed again yesterday, the first workday after a subway explosion took at least 40 lives Friday in what officials now say was a suicide bombing.
But the atmosphere was not business as usual, as flags around the city flew at half-staff, red carnations lay on a subway platform near the site of the blast and officials warned of more attacks.
The first of the dead were buried yesterday as more than 100 people remained hospitalized, including more than 20 in critical condition.
Three days after the explosion, President Vladimir V. Putin had made no further comment since remarks on Friday, when he said he was certain that Chechen separatists were involved.
Putin, who is expected to be re-elected next month, has presented himself as a strong leader, and the war in Chechnya is seen by many as his war.
Vyacheslav Ushakov, deputy chief of the Federal Security Service, said investigators believe the explosion was the work of a suicide bomber. He warned that future attacks could be directed at nuclear power stations and public transportation.
There has been a long string of terrorist attacks around the country that have been linked to Chechen rebels. But the bombing of the Metro, which carries 10 million passengers a day, has brought a heightened sense of insecurity to Moscow.
Whispers of a government cover-up have found their way into print and a national television news broadcast. The main television channel quoted the newspaper Gazeta as saying that Moscow Mayor Yuri M. Luzhkov had a secret list of the dead and that the toll was much higher than officials indicated.
The attack has sharpened a distrust of people from the Caucasus. Hard-line nationalists have made racist comments.
Vladimir V. Zhirinovsky demanded the expulsion of people from the Caucasus and called for night patrols and curfews.