Terror attacks at an airport and subway station in Brussels, Belgium on Tuesday killed at least 31 people and injured more than 180, including about a dozen Americans. The city went into lockdown for hours, prompting European countries and the U.S. to strengthen security. The Islamic State group claimed responsibility for the bombings. Two suicide bombers each set off bombs seconds apart from one another at the Brussels airport. Both men died in the attacks, while a third suspect is still at large, according to Belgian prosecutors. About an hour later, another bomb exploded on a subway train as it left the station just blocks from the European Union’s headquarters. Investigations are underway as European security forces continue to search for other individuals who may be linked to the attacks. “Our country and our citizens have been hit by blind, violent and cowardly attacks,” Belgian Prime Minister Charles Michel said. “We are confronted with a challenge, a difficult challenge, and we must face it by standing united, showing solidarity and staying together.”

European Union — a politico-economic union of 28 member states that are located primarily in Europe and primarily headquartered in Brussels, Belgium Islamic State — a militant movement that has conquered territory in western Iraq and eastern Syria and follows an Islamic fundamentalist doctrine intelligence-gathering — a system through which information about a particular entity is collected and often shared through the use of more than one inter-related sources