As the evening draws on in St Petersburg, locals are paying tributes to those killed and injured on Monday's attack.
The cause of the explosion has yet to be confirmed. Here is a round-up of what we know:
- The explosion happened at about 14:30 local time (11:30 GMT) between Sennaya Ploshchad and Tekhnologichesky Institut stations
- Up to 10 people were killed with at least 37 injured, Russia's health minister says
- Another device was later found at a nearby station and made safe
- Passengers were captured on video escaping a smoke-filled platform
- President Vladimir Putin said all causes, including terrorism, were being investigated
- No-one has said they were behind the blast but local media released CCTV footage of a bearded man
- Foreign leaders have condemned the incident, with US President Donald Trump describing it as a "terrible thing".