Many of the people killed in the Moscow suicide attacks were students
By Sarah Rainsford
BBC News, Moscow
Throughout the day, weeping crowds have arrived at Moscow's cemeteries clutching icons, flowers and photographs of relatives and friends - some of the 39 people killed in Monday's double suicide bomb attack on the city's Metro.
Many of the mourners were young students. Their friends had been travelling to university when the two female bombers detonated their suicide belts.
The bodies of some of the women's other victims have been sent for burial in places as far flung as Sevastapol, on the Black Sea, and the former Soviet republics of Moldova and Tajikistan.
Moscow has always attracted a diverse population, with its relative wealth, vibrancy and opportunities.
Four days after the bomb blasts, the mood in the capital is sombre and nervous.
The emergencies ministry has recorded a significant rise in the number of incoming calls.
Many are false bomb alarms or reports of suspicious packages.
Others come from worried residents seeking advice and support. Often it is because they are afraid to get back on the Metro.
Finger of blame
Late last night, there was chilling news that they may have good reason to worry.
MOSCOW METRO ATTACKS
March 2010: Two suicide bombers blow themselves up at Lubyanka station and Park Kultury station, killing 39 people
August 2004: Suicide bomber blows herself up outside Rizhskaya station, killing 10
February 2004: Suicide bombing on Zamoskvoretskaya line, linking main airports, kills 40
August 2000: Bomb in pedestrian tunnel leading to Tverskaya station kills 13
February 2000: Blast injures 20 inside Belorusskaya station
January 1998: Three injured by blast at Tretyakovskaya station
June 1996: Bomb on the Serpukhovskaya line kills four
The leader of the Islamist insurgency in the North Caucasus issued a video statement saying that he had ordered the twin bomb attack on the Moscow metro.
Dressed in military fatigues and filmed in a field, Doku Umarov claimed the bombs were his revenge for what he said was the killing of civilians in Chechnya in February by Russian security forces.
He promised more attacks to come, to bring the conflict from the Caucasus to the streets of Russian cities.
There has been no official reaction to that statement, but Russian President Dmitry Medvedev and the security service, FSB, had already pointed the finger of blame at the volatile North Caucasus.
Now the head of the FSB has said the service knows who is behind the bombing and several people have been detained.
A year ago, Mr Medvedev announced that almost a decade of fighting in Chechnya was officially over.
But what started as a war for independence in the southern Russian republic has gradually morphed into an extremist Islamist insurgency, and seeped across the border into Ingushetia and Dagestan.
Thirty-nine people were killed in the attacks on the Metro
On Wednesday, there was a stark reminder of that - with another double suicide attack, this time in Dagestan.
Nine police officers were killed in the town of Kizlyar close to the Chechen border.
So on Thursday, Mr Medvedev made a surprise flying visit to Dagestan, bringing together regional leaders from the North Caucasus as well as security chiefs from Moscow.
Once again, his language was strong.
we've managed to tear the heads off the most odious bandits," Mr Medvedev said, in a speech broadcast on state television.
"Clearly that wasn't enough. But we will find them all in due course, and punish them all just like we punished others before. That is the only way."
His clear aim was to reassure Russians across the country that he and his team were in control and protecting them.
But Muscovites had thought the days of violent attacks on their city had passed.
Now, as the families of the bomb victims here bury their dead - and with the threat of more violence hanging over them - it is far from clear that the president's reassurances have been heard.