Just 40 days before the Sochi Olympics, a female suicide bomber detonated an explosive inside a train station in Volgograd, killing at least 14 people and injuring many more, and raising safety concerns leading into the games. 

Around 12:45 p.m., a female suspect was stopped by a police officer near the metal detectors close to the train station's entrance. The train was packed with people travelling for the upcoming holidays. A video aired on Russian news shows a quick orange flash, followed by plumes of thick smoke coming from the entrance. The bomb was packed with 10 kg of TNT and additional shrapnel, according to Russia's National Anti-terrorism Committee spokesperson Vladimir Markin.

An estimated 33 people were injured, some critically, according to Russian health officials. The attack was "thought to have been carried out by a female suicide bomber," Markin said, according to a statement carried by RT.com. The suspect has not yet been identified. 

Volgograd is roughly 690 kilometers northeast of Sochi, and lies between Moscow and the North Caucasus region, where Chechnya and Dagestan are located. Terrorist attacks have plagued the region as Islamist independence factions have clashed with Russian government forces. In October, a female suicide bomber killed six people in Volgograd after detonating an explosive on a local bus. 

But two deadly attacks ahead of the 2014 Winter Olympics in Sochi will only stoke security concerns ahead of the games, which Putin has promised will be the safest ever.