Following are some of the deadly attacks in Western Europe over the past two years:
Dec. 19, 2016 - A truck ploughs into a crowded Christmas market in central Berlin, killing 12 people and injuring 48. German Chancellor Angela Merkel says authorities are assuming it was a terrorist attack.
July 26, 2016 - Two attackers kill a priest with a blade and seriously wound another hostage in a church in northern France before being shot dead by French police. Five people are initially taken hostage. French President Francois Hollande says the two hostage-takers had pledged allegiance to Islamic State.
A patient shoots at a doctor in a university clinic in Steglitz, a southwestern district of Berlin, before shooting himself. German police say there is no sign of a link to terrorism.
July 24, 2016 - A 21-year-old Syrian refugee is arrested after killing a pregnant woman and wounding two people with a machete in the southwestern German city of Reutlingen, near Stuttgart. "Given the current evidence, there is no indication that this was a terrorist attack," police say.
- A Syrian man wounds 15 people when he blows himself up outside a music festival in Ansbach in southern Germany. Islamic State claims responsibility for the attack. The 27-year-old arrived in Germany two years ago and claimed asylum. He had been in trouble with the police repeatedly for drug-taking and other offences and had faced deportation to Bulgaria.
July 22, 2016 - An 18-year-old German-Iranian gunman apparently acting alone kills at least nine people in Munich. The teenager had no Islamist ties but was obsessed with mass killings. The attack was carried out on the fifth anniversary of twin attacks by Norwegian mass murderer Anders Breivik that killed 77 people.
July 18, 2016 - A 17-year-old Afghan refugee wielding an axe and a knife attacks passengers on a train in southern Germany, severely wounding four, before being shot dead by police. Islamic State claimed responsibility for the attack.
July 14, 2016 - A gunman drives a heavy truck into a crowd celebrating Bastille Day in the French city of Nice, killing 86 people and injuring scores more in an attack claimed by Islamic State. The attacker is identified as a Tunisian-born Frenchman.
June 14, 2016 - A Frenchman of Moroccan origin stabs a police commander to death outside his home in a Paris suburb and kills his partner, who also worked for the police. The attacker told police negotiators during a siege that he was answering an appeal by Islamic State.
March 22, 2016 - Three Islamic State suicide bombers, all Belgian nationals, blow themselves up at Brussels airport and in a metro train in the Belgian capital, killing 32 people. Police find links with the November attacks in Paris.
Nov. 13, 2015 - Paris is rocked by multiple, near simultaneous gun-and-bomb attacks on entertainment sites around the city, in which 130 people die and 368 are wounded. Islamic State claims responsibility. Two of the 10 known perpetrators were Belgian citizens and three others were French.
Jan. 7-9, 2015 - Two Islamist militants break into an editorial meeting of satirical weekly Charlie Hebdo on Jan. 7 and rake it with bullets, killing 17. Another militant kills a policewoman the next day and takes hostages at a supermarket on Jan. 9, killing four before police shoot him dead. The attacks prompt a worldwide solidarity movement with the slogan "Je Suis Charlie" (I am Charlie).
May 24, 2014 - Four people are killed in a shooting at the Jewish Museum in central Brussels. The attacker was French national Mehdi Nemmouche, 29, who was subsequently arrested in Marseille, France. Extradited, he is awaiting trial in Belgium.
(Editing by Sonya Hepinstall, Raissa Kasolowsky and Frances Kerry)