Two suicide bombings in as many days have left 31 people dead and dozens more wounded in Russia.
Both bombings happened in the southern city of Volgograd. The latest was during the city's morning rush hour on Monday, on a bus passing near a busy market. At least 14 people were killed and 30 were hurt in the explosion. That came less than 24 hours after the first attack killed 17 people in the city's train station.
Russian authorities are calling both incidents terrorist attacks. They say the bombs could have been made in the same place, linking the attacks. This is the second set of bombings Volgograd has seen in the last two months. Officials are now working to identify the bombers. The head of Russia's Investigative Committee said Sunday's bomb was set off by a person near the station's metal detectors, but they are unsure whether it was a man or a woman.
Volgograd is a major travel hub for people going to the upcoming Winter Olympics in Sochi, which are less than six weeks away. This recent bout of terrorist activity has organizers worried for the safety of athletes and spectators going to the games.
No one has claimed responsibility for the recent bombings, but one terrorist group in that area announced in July that they would use violence to disrupt the Olympics, which many Muslim terrorists see as a provocation from western society.
Security around Sochi is tight. The Russian government has tens of thousands of soldiers and policemen set to protect the Olympic Games, and has set some of the most extensive security measures and identity checks ever seen at an international sporting event. But because of this, it looks like militants are targeting the surrounding areas and transportation hubs.
The United States has condemned the attacks and has pledged to help Russia prepare security for the Sochi Olympics.