Two terrorists were involved in a suicide bomb attack at Moscow's Domodedovo International Airport that killed 35 and injured up to 180 on Monday, a law enforcement source said, RIA Novosti reported.
Both died in the explosion that ripped through the international arrivals zone at 4:40 p.m. (13:40 GMT), as friends and taxi drivers were meeting arriving passengers.
The blast was equivalent to 5 kilograms of TNT and the bomb was packed with metal objects to cause maximum damage. Earlier reports said that the bomb was equivalent to 7 kg of TNT.
"The blast occurred when a suspected female terrorist opened a bag. She was accompanied by a man whose head was ripped off by the explosion," the source told RIA Novosti.
"It cannot be ruled out that the terrorists wanted to leave the explosive device in the hall but the bomb was detonated inadvertently or by a remote control device," he said.
"The terror attack was done according to a scheme that is used by terrorists from the North Caucasus region," he said. "The [2004] blasts at the Rizhskaya subway station and other explosions in the Moscow metro [2010] were carried out similarly, when the terrorists were accompanied by militants."
Reports suggest the terrorists were driven to the airport, Moscow's busiest, by an accomplice.
The bombing was the worst terror attack since two female suicide bombers from the volatile North Caucasus republic of Dagestan blew themselves up at two of the capital's subway stations last March, killing 40.
Police have hinted the latest outrage may be linked to the Islamist radicals in the North Caucasus.
Three suspects are being sought over the bombing.
Russian President Dmitry Medvedev said there were obvious security lapses at the airport, while the country's national anti-terrorism committee (NAC) said insufficient security measures were to blame, as the terrorists entered the airport unchecked.