Russian authorities say at least nine people have been killed and 50 others injured in an explosion on the metro system in the city of St. Petersburg, Russia's second largest city.
St. Petersburg Metro Explosion
5
A helicopter flies over the fire trucks after an explosion at Tekhnologichesky Institut subway station in St.Petersburg, Russia, April 3, 2017.
6
In this image taken from video footage, emergency services work outside Sennaya Square metro station in St Petersburg, Russia, April 3, 2017.