The trolley-bus in Volgograd was blasted by a male suicide bomber, his remains have been sent for a DNA study, official spokesman for the Investigative Committee Vladimir Markin has told Interfax.

"One can tentatively say now that the explosive device was activated by a man. Fragments of his body have been retrieved and sent for a DNA study for identification," he said.

"Actually only the frame is left of the trolley-bus. The roof is absent. The explosion was so powerful that it broke the windows in a five-storey building across the street," Markin said.