Members of the emergency services work at the site of a bomb blast on a trolleybus in Volgograd December 30, 2013.

The suicide bomber who killed 16 people and injured dozens in the Volgograd railway station in Russia has been identified to be a woman in the preliminary investigation. Her name is Oksana Aslanova.

The blast took place on Sunday, Dec 29, at around 1 pm. The woman detonated a shrapnel-filled bomb in front of a metal detector at the station entrance, Reuters reports. The attack is being treated as a terrorist activity. The investigation committee identified around 10 kg TNT in the explosive.

This is the second attack in Volgograd in the last 3 months. Another woman suicide bomber was responsible for killing six passengers on a city bus in Oct. It happened in a city which is about 900 km away from Moscow.

The suicide bomber reportedly arrived from the capital of Dagestan which is primarily a Muslim region. She disembarked from one bus which was heading to Moscow. One hour later, the blast took place. Russian President Vladimir Putin has instructed the authorities to take every necessary action to help the bombing victims.

Islamist terrorists in the North Caucasus region have been regularly instigating one attack after another since 2000 when Mr Putin became the president of the country. Their present assignment seems to be the disruption of the Olympics which is going to start in Sochi in Feb 2014.

Video footage captured the blast which looked like a huge "orange fireball" inside the station. Soon after, grey-coloured smoke came out of the shattered windows. The station happens to Stalinesque architecture with one clock-tower. The station was busier than how it usually is as people were traveling home on the occasion of the New Year which is one of the major holidays in the country.

Meanwhile, the United Nations, the United States and Canada have been among the first to criticise the terror attack. U.S. spokesperson Jen Psaki has stated that it condemns the Volgograd attack "in the strongest terms."

Watch a video of the suicide bombing in Russia here.