(Reuters) - A gunman in police uniform killed at least 84 people in a ferocious attack on a youth summer camp of Norway's ruling Labor party, hours after a bomb killed seven in Oslo.
Here are details of recent bomb attacks and plots around Europe.
* MADRID BOMBINGS: 2004
-- On March 11, 2004 10 bombs hidden in sports bags exploded on four packed commuter trains at the height of the morning rush hour in Madrid, killing 191 people and wounding 1,700.
-- The bombings were Europe's deadliest Islamist militant attack. Courts convicted 21 people in 2007 of the attacks. Four of the 21 had their convictions overturned in 2008.
-- Three weeks after the blasts, seven men including two suspected bombing ringleaders blew themselves up in an apartment after police closed in on them. The blast killed a policeman.
* LONDON BOMBINGS: 2005
-- Four suicide bomb blasts on London transport during the morning rush hour on July 7, 2005 killed 52 people and injured about 700 in the first Islamist suicide bombing attacks in western Europe. On July 21, four men made a failed attempt to carry out a second wave of attacks on three London underground stations and a bus.
* LONDON AND GLASGOW: 2007
-- Police defused two car bombs packed with petrol, gas and nails near London's theater district. A day later, a car laden with petrol was rammed into a terminal building at Glasgow Airport. Bilal Abdulla was born in Britain and held a British passport but was an Iraqi national. He was convicted in December 2008. His co-defendant Mohammed Asha was found not guilty, and his accomplice Kafeel Ahmed died of injuries sustained in the Glasgow attack.
* BARCELONA PLOT: 2009
-- Spain's high court on December 14, 2009 jailed 11 men for up to 14 and a half years for attempted suicide bombings on Barcelona's metro in 2008. The group, including 10 Pakistanis and one Indian, were very close to developing explosives to be used in the attacks planned for January 18-20, 2008, according to the ruling.
* AIRLINE PLOT: 2009
-- Three Britons were found guilty in September 2009 of plotting to simultaneously destroy at least seven planes carrying over 200 passengers each between London's Heathrow airport and the United States and Canada in August 2006 using explosives hidden in soft drink bottles, prosecutors said. The plot was hatched in Pakistan just months before the men were arrested in August 2006.
* SWEDEN AND DENMARK: 2010
-- Taymour Abdulwahab, a Swedish national of Middle Eastern descent, was killed in an attempted attack on downtown Stockholm on December 11, after a bomb belt he was wearing went off prematurely.
-- The blasts followed emailed threats referring to Sweden's troops in Afghanistan and to Swedish artist Lars Vilks cartoons of the Prophet Mohammad as motives. A local newspaper Nerikes Allehanda, based in Orebro in central Sweden published drawings depicting Mohammad, by Vilks in 2007, leading to protests against the newspaper and death threats against Vilks.
-- Danish police arrested five people on December 29 suspected of planning an attack to kill as many people as possible in a building housing Danish daily Jyllands-Posten that outraged Muslims in 2005 with cartoons of Prophet Mohammad.
-- A suspected right-wing Christian gunman in police uniform killed at least 84 people in an attack on a youth summer camp of Norway's ruling Labor party on Utoeya, a small pine-clad island, hours after a bomb killed seven in Oslo.
-- The bomb shook Oslo's center and blew out the windows of the prime minister's building and damaged the finance and oil ministry buildings. Police also found undetonated explosives on the island.