The blasts scene at Brussels Zaventem Airport. [Photo: cnr.cn]

BEIJING, March 22 -- At least 13 people were killed in two explosions Tuesday at the Brussels airport and 15 people were killed in another explosion at a metro station in the Belgian capital.

The following are major terrorist attacks that have hit the European Union over the past several years.

On March 11, 2004, at least 190 people were killed and more than1,200 injured in a series of bomb attacks on the Madrid train system during the morning rush hour and three days before the Spanish general election.

On July 7, 52 people were killed and more than 700 injured in suicide bomb attacks in London's underground system.

On March 19, 2012, three children and an adult were killed in a shooting outside a Jewish school in the southwestern French city of Toulouse in the morning. The shooting was the third of its kind in the region in a week. On March 11 and March 15, three soldiers were killed in two similar shootings in Toulouse and in nearby Montauban.

On Jan. 7, 2015, the Paris office of Charlie Hebdo, a satirical newspaper, was attacked by heavily armed men. Twelve people were killed, including the chief-editor of the newspaper. On Jan. 8, a20-year-old policewoman was killed in a shooting in Montrouge, south Paris. On Jan. 9, at least two people were killed and one injured in the Porte de Vincennes hostage crisis in East Paris.

On June 26, 2015, two men entered by force a U.S. gas company in Isere, southeast France, leaving behind several wounded victims. A decapitated body was found at the site with an Islamist State flag aside.

On Nov. 13, 2015, about seven simultaneous shootings and fresh explosions rocked central Paris during the evening. One of the shootings resulted in a hostage taking crisis at the Bataclan theater and concert hall, killing at least 140 people and wounding many.