Last Tuesday morning, March 22, suicide bombers believed to be connected to ISIS, the terrorist group behind the Paris attacks in November 2015, detonated bombs causing two explosions at Brussels Airport and a following explosion at Maalbeek Metro Station which have killed at least 31 people and wounded up to 270 others.

Motives for the attack have yet to be confirmed, although the Guardian posits it may be retribution in response to the arrest of Salah Abdeslam, who was detained in Brussels the previous Friday.

According to a developing story at the Independent, an eye witness described the scene at the airport as horrific. “It was atrocious. The ceilings collapsed. There was blood everywhere, injured people, bags everywhere.”

The known suicide bombers involved are reported to be dead. Ibrahim (or Brahim) el-Bakraoui and Najim Laachraoui were responsible for the explosions at the airport, and Khalid el-Bakraoui, Ibrahim’s brother, was responsible for the explosions at Maalbeek Metro station.

However, two others related to the attacks are believed to be still on the loose. An unknown man seen in airport CCTV footage and a fifth unidentified man have yet to be found.

Leaders across the European Union condemned the attacks and expressed their condolences towards the victims. Justice minister of Germany Heiko Maas called the event “a black day for Europe” on Twitter, and that “the horrible events in Brussels affect us all.” Mark Rutte, Dutch Prime Minister, said Belgium was “hit by cowardly and murderous attacks,” while Francois Hallande, French President, said that “terrorists struck Brussels, but it was Europe was targeted.”