Early reports say 15 people died in the Monday morning terrorist act in a trolley-bus in Volgograd, and 23 more were wounded, Volgograd region vice governor Vasily Galushkin told Interfax from the scene.

"First aid worked promptly. All the wounded have already been taken to hospital. They are now being identified," he said.

"The picture is horrible. Now the main work will have to be done by investigative bodies. Governor of the region, Vice Premier Olga Golodets and Health Minister Veronika Skvortsova are here now," Galushkin said.