RT News - April 04, 2017 (17:00 MSK)

Smoke can be seen rising from Sennaya Square metro station, where the blast reportedly took place. People are covering their faces to protect themselves from the smoke. There are reports that all metro stations have been evacuated and closed, that's according to the Russian National Anti-terrorism committee. There are also unconfirmed reports the explosive device was rigged with shrapnel. The Saint Petersburg prosecutors office has launched an investigation into the blast. President Putin has expressed condolences to the families of those killed in the incident. Putin added all possible causes for the blast are being considered.