Live updates: St. Petersburg metro explosion

At least 10 people were killed Monday in an explosion on a metro train in St. Petersburg, Russia, authorities there said. Russian President Vladimir Putin, who was in St. Petersburg for a meeting with Belarusian President Alexander Lukashenko, said the cause of the blast was not clear. The Russian antiterrorism committee says it has found and deactivated a bomb at another St. Petersburg subway station. Reuters is providing live coverage of the explosion and its aftermath. See below for the