Russia's state investigative committee said on Tuesday that the deadly St Petersburg metro blast was caused by a bomb that had possibly been detonated by a man whose body parts were found in one of the train carriages.
"It has been ascertained that an explosive device could have been detonated by a man, fragments of whose body were found in the third carriage of the train," the committee, which has sweeping powers, said in a statement.
"The man has been identified but his identity will not be disclosed for now in the interests of the investigation," the statement added.
An injured person is helped by emergency services outside Sennaya Ploshchad metro station, following explosions in two train carriages at metro stations in St. Petersburg, Russia April 3, 2017.