Follow all of the latest developments as they happen.
Final Summary
-- An explosion ripped through a subway car in the Russian city of St. Petersburg, killing at least 10 people and injuring dozens of others in what officials suspect was a terrorist attack.
-- An undetonated explosive device was found at another subway station, Ploshchad Vosstaniya.
-- President Vladimir Putin said he has been briefed by security officials on the incident and that authorities were examining a possible terrorism link.
-- Western governments expressed condolences and solidarity in the aftermath of the attack.
All metro stations now closed in St. Petersburg after blast.
Putin offers condolences to families of victims of St. Petersburg blast.
Putin says authorities probing all possible causes for the metro blasts in St. Petersburg, including terrorism.
Scenes after blast in St. Petersburg metro.
Horrific photos from St. Petersburg:
Video showing the aftermath of the blast.
There have been unconfirmed reports of a second explosion:
Aftermath from blast in St. Petersburg metro.
