At least five people were killed and 17 injured when a bomb blast tore through a bus in Volgograd in southern Russia on Monday (October 21). A female suicide bomber reportedly carried out the attack.

The bombing took place at about 2pm local time inside a packed bus with about 40 passengers onboard. Local media reported the bus was blown up by a female suicide bomber strapped with explosives. The woman allegedly was a militant leader's wife and recently adopted Islam.

Media reported that preliminary data suggested that a hand grenade went off inside the bus and a second grenade was reportedly found and diffused.

At least 17 people were wounded, seven of them in grave condition. There was no immediate claim of responsibility.

According to Reuters: "Volgograd is a city of around one million people that lies 900 km (560 miles) southeast of Moscow and a few hundred kilometres north of the North Caucasus and Black Sea resort city of Sochi, where Russia will host the 2014 Winter Olympics.

"President Vladimir Putin has staked his reputation on the Games and ordered authorities to boost security in the North Caucasus, where the Islamist insurgency is rooted in two post-Soviet wars pitting Chechen separatists against the Kremlin."