A fatal explosion has rocked the St. Petersburg metro system, and if it turns out to be a terrorist attack, it would be the latest in a long line of attacks targeting Russia in recent years. Some of the deadliest include the following:
* October 2015: Militants from local affiliate of Islamic State down a Russian airliner en route to St. Petersburg over Egypt, killing all 224 people on board.
* October 2014: Suicide bomber wearing a police uniform blows himself up in Grozny, the capital of Chechnya, killing five policemen and wounding 12 others.
* December 2013: Back-to-back suicide bombings in the southern Russian city of Volgograd kill 34 and injure 100 others.
* January 2011: Suicide bomber blows himself up at Domodedovo Airport, Moscow's busiest, killing 35 and injuring 180 people.
* March 2010: Two suicide bombers attack Moscow subway system, setting off their explosives about 30 minutes apart on two trains during rush hour, killing at least 40 and injuring more than 100.
* November 2009: A bomb explodes under the high-speed Nevsky Express train travelling between Moscow and St. Petersburg, causing a derailment that kills 28 and injures nearly 100.
* October 2005: Islamic militants launch a series of attacks on police in Nalchik, capital of the tense Kabardino-Balkariya republic near Chechnya. Chechen rebels claim credit for the attack, in which 139 people were killed, including 94 militants.
* September 2004: About 30 Chechen militants seize a school in the southern town of Beslan and take hundreds of hostages. The siege ended in a bloodbath two days later, with more than 330 people, about half of them children, killed.
* August 2004: A suicide bomber blows herself up outside a Moscow subway station, killing 10 people.
* August 2004: Two female suicide bombers bring down two Russian airliners that took off from Moscow's Domodedovo airport, killing 90 people. Chechen rebels claim responsibility .
* February 2004: A suicide bomber strikes a subway car in Moscow during rush hour, killing 41 people and injuring more than 100.
* December 2003: A suicide bombing on commuter train in southern Russia kills 44 people, two days before Russian parliamentary elections.
* October, 2002: Chechen militants take 800 people hostage at a Moscow theatre. Two days later, Russian special forces storm building and 129 hostages and 41
* August 1999: Four apartment building bombings kill about 300 people in Moscow and two other Russian cities. The Kremlin names the attacks as a key reason for sending troops back into Chechnya the following month.
