The bodies of victims of a suicide bomb attack on a Russian train station Sunday are laid outside as investigators examine the scene.br br A shrapnel-filled bomb was detonated by an assailant in front of a metal detector inside the entrance hall of this station, killing 16 people.br br The blast blew out nearby windows.br br Authorities initially said the attacker was a woman, but later said a man could have set off the blast.br br Cleanup operations continued well into the night and security stayed on site.br br Deadly attacks like these, the second in three days, pose a security challenge for President Vladimir Putin now that the Russian winter Olympics are 40 days away.