The fatal bombing of the Boston Marathon is not the first time a sporting event has been targeted. Gunmen, suicide bombers and kidnappers have attacked athletes and venues across the world - from Munich, to Angola, Pakistan and the United States. They have been separatists, militants and activists.
Here are some of the attacks:
September 1972: Palestinians going by the name of "Black September" kill two Israeli athletes and take nine hostage at the 1972 Munich Olympics, demanding that Israel release 200 political prisoners. All the Israeli hostages are later killed. A German police officer and five of the kidnappers also die.
July 1996: An 18kg (40 pound) pipe bomb explodes during a nighttime music concert at the Centennial Olympic Park, killing one person and injuring more than 100 others. In 2005, Eric Robert Rudolph admits responsibility for the attack. He says he wanted to shame the U.S. for its legalization of abortion but had planned to knock out Atlanta's power grid not to harm innocent civilians.
May 2002: Seventeen people are injured when a car bomb is detonated near the Bernabeu Stadium in Madrid hours before a Champions League semifinal between Real Madrid and Barcelona FC. UEFA makes security checks before deciding to go ahead with the match. The Basque newspaper Gara says the Basque separatist group ETA gave advance warning of the attack.
2006: Fifteen members of Iraq's Olympic taekwondo team are kidnapped for ransom while driving to Jordan in May. A year later, 13 of their bodies are found.
The same month the Iraqi tennis coach and two of his players are shot dead. The BBC reports that the men were shot by militants who objected to the players wearing shorts.
In July, gunmen snatched more than 20 Iraqi sports officials -- including the head of Iraq's Olympic Committee from an Iraq National Olympic Committee meeting in Baghdad. It remains unclear what happened to the officials.
In December four football players were wounded in a mortar attack while training in Baghdad.
April 2008: A senior Sri Lankan Cabinet minister and at least 13 other people -- including police and government officials -- are killed in a suicide bombing at the start of a marathon just outside the capital city Colombo. The minister had been waving the starting flag for the race when he was killed. Tamil Tigers -- then fighting for an independent Tamil state -- are suspected of being behind the blast.
March 2009: The Sri Lankan cricket team is attacked as it travels by bus to a match in Lahore, Pakistan. Seven players and an assistant coach are killed, as are at least six Pakistani police providing security for the team. Local police say they believe the gunmen wanted to kidnap the cricketers to exchange them for jailed militants.
January 2010: Gunmen open fire on the Togo national soccer team, in Angola killing the team's assistant coach, its communication officer and the bus driver dead. The attack is claimed by separatist group Forces for Liberation of the State of Cabinda. Cabinda is a disputed oil-rich enclave in the Democratic Republic of the Congo, where the soccer team was heading to play in the African Cup of Nations tournament.
April 2013: At least three people are killed when two bombs explode at the Boston Marathon on the east coast of the United States.