The Russians were apparently warned of the upcoming attack. Additionally, it turns out the group tried to commit on attack on New Year's Eve (via AFP):
The suicide bomber who killed 35 people at Moscow's Domodedovo airport may have been part of a group despatched by militants in the Northern Caucasus to bomb the capital, reports said Tuesday.
The Kommersant daily, citing its own sources, said the Russian special services became aware of the risk of an attack when a small building on the site of a Moscow sports club was completely destroyed by an explosion late on December 31.
It said that the explosion was caused by a woman from the Northern Caucasus who had accidentally blown herself up due to carelessness with explosives.
"Militant leaders had despatched women to carry out an attack on the night of New Year," it said. "But one of them exploded her charge prematurely."
"It is not excluded that she did not come to Moscow alone but with several groups of suicide bombers. And a second woman blew herself up yesterday," said the paper.
The woman who blew herself up by mistake was a 'black widow'. After last year's terror attack in the Moscow Metro, officials said they were looking for 21 more such women.
The authorities also then started a search for three suspects from Chechnya who were believed to have been preparing another suicide bomber.
The trio then accompanied the woman to Domodedovo airport Monday, where she set off her charge. They then disappeared without trace.
"The explosion occurred the moment the presumed female suicide bomber opened her bag," the state-run news agency quoted the unnamed security official as saying.
"The terrorist was accompanied by a man. He was standing beside her and (the blast) tore off his head."