Russia is reeling from a mass shooting and blaze at a Moscow rock concert, which the government has labeled a "terrorist attack."
Here is a look back at previous attacks on the city in the past 25 years.
Apartment building bombed, 118 dead (1999)
A bomb blast in the early hours of Sept. 13, 1999, at an eight-story apartment building in southeast Moscow kills 118 people.
The attack was one of five on apartment buildings that left a total of 293 people dead over a two-week period in Moscow and southern Russia.
Moscow blames the attacks on separatist "terrorists" from the mainly Muslim North Caucasus republic of Chechnya.
President Vladimir Putin uses the attacks to justify launching a campaign to crush a separatist insurgency in Chechnya.
Theatre hostage crisis, 130 dead (2002)
A group of 21 male and 19 female Chechen rebels storm Moscow's Dubrovka theatre on Oct. 23, 2002, during a musical and take more than 800 people hostage.
The standoff with security forces lasts two days and three nights.
It ends when the security forces inject gas into the theatre to overpower the attackers and then storm it. A total of 130 hostages are killed. Most died by choking on the gas.
Rock concert attack, 15 dead (2003)
On July 5, 2003, two female suicide bombers, identified by Russia as Chechen separatists, blow themselves up during a rock concert at the Tushino airfield near Moscow, killing 15 people and injuring around 50 others.
Around 20,000 fans had come to hear some of Russia's top bands at the annual Krylya (Wings) festival.
Metro bombing, 41 dead (2004)
On Feb. 6, 2004, a little-known Chechen group detonates a bomb in a packed Moscow subway during morning rush hour, killing 41 people.
Metro suicide attack, 40 dead (2010)
On March 29, 2010, another two female suicide bombers blow themselves up on the Moscow subway.
Forty people are killed in the attacks, one of which targets Lubyanka station, beside the headquarters of the FSB intelligence services.
The two bombers were from the volatile North Caucasus region of Dagestan.
The Caucasus Emirate group of Chechen rebel leader Doku Umarov claims responsibility.
Airport attack, 37 dead (2011)
On Jan. 24, 2011, a suicide bomber strikes in the arrivals hall of Moscow Domodedovo international airport killing 37 people.
The Caucasus Emirate group claims responsibility for the attack.
