A picture of the Volgograd bus (Ministry of Civil Defence, Russia)
A bomb has gone off inside a bus in the central Russian city of Volgograd killing six people, according to Interfax News Agency.
The blast also wounded 20 people, according to reports. Police have opened a criminal case for murder.
"According to preliminary data, an unknown explosive device went off inside the bus, that's why a terrorist act may be viewed as one of the possible causes of the blast," a source in the Investigative Committee told Interfax.
The source said detectives suspect a female suicide bomber to be responsible for the blast. MORE TO FOLLOW...
People walk at the Mamayev Kurgan (Mamayev Hill) World War Two memorial complex, with the statue of Mother Homeland in the background during celebrations in the city of Volgograd (Reuters)
