The bombing comes exactly one week after explosions on two Russian planes killed all 90 people aboard. Authorities have said those bombings could be tied to two Chechen female passengers aboard the planes.
A militant Muslim web site published a statement on behalf of the “Islambouli Brigades,” claiming responsibility for the Moscow bombing. The group had also claimed responsibility for the plane crashes, the Associated Press reported. The statements, however, could not be confirmed.
According to the statement, the subway bombing was in response to the policies of Russian President Vladimir Putin “who slaughtered Muslims time and again.” Putin has refused to negotiate with rebels in Chechnya, pushing for their elimination.
In Tuesday’s attack, it appeared the woman tried to enter a metro station, Mayor Yuri Luzhkov said.
“She… was at the door when she saw two policemen. She was scared and turned and decided to destroy herself,” said Luzhkov.
“Up to 1 kg (2.2lb) of explosive was used,” Luzhkov told reporters. “This is an unusual amount of explosive for a woman suicide bomber. There was a desire to cause maximum damage.”
Of the 51 wounded, 49 were hospitalized, Federal Security Service spokesman Sergei Ignatchenko told NTV television. The death toll is likely to rise, he added.
Tuesday was the last day of the summer holiday before classes start again tomorrow — parents and children were out shopping for last-minute school items.
Luzhkov said shortly after the blast that four children and 11 women were among the injured.
“It was like a big thunder clap. I was just coming out of the shop. There was one explosion, then another small one, probably from gas,” Alexei Borodin told Reuters.
“I saw five people who could not stand up. And there were other people who were in small bits. There was one man without a stomach shouting: ‘Where are the police?'”
This is the second bombing of a Moscow metro in the last six months. In February more than 40 people died in an explosion inside a subway car.
On Sunday, Chechnya held elections that led to the expected victory of a new Moscow-backed president, Alu Alkhanov. He will replace Akhmad Kadyrov, who was assassinated May 9 by a bomb that killed 23 others during a Victory Day ceremony.
In the past 21 months, nearly 370 people have died in terrorist attacks tied to the battle between rebels in the separatist republic of Chechnya and Russian authorities.