Tuesday is a day of national mourning in Russia, following Monday's double suicide bombing in the Moscow subway system.

Flags outside government buildings are flying at half staff. A temporary memorial of flowers and candles are also at the two stations where the deadly attacks occurred.

The death toll climbed to 39 Tuesday morning after a woman died from her wounds.

On Monday, two female suicide bombers detonated explosive belts during the morning rush-hour at two central Moscow subway stations.

The first explosion took place just before 8 a.m. at the Lubyanka station in central Moscow, right underneath the offices of Russia's security service, the old KGB. The second explosion happened about 45 minutes later near Gorky Park.

Officials blamed the carnage on rebels from the Chechnya region. The attacks are believed to be the work of so-called "black widows," the wives or relatives of Chechen rebels killed by the Russians. There have been fears of retaliation recently after Russian police killed several Islamic militant leaders in the North Caucasus.

"It can happen anywhere," Moscow resident Alexander Kondrashin said. "No one is safe from this kind of thing."

"I think that it's disgrace, that it's scary and that we are not protected," said Marina Belyakova, another Moscow resident.

The blast may have killed ordinary Russians, but it was also aimed at President Vladimir Putin, who has built much of his political capital on claims that he defeated Chechen separatists 10 years ago.

However, Moscow is unlikely to hit back at the rebels with massive firepower. It has installed friendly leaders in Chechnya, so the barbaric, devastating artillery and carpet bombing used in the 1990s war against the Chechens is out of the question.