terror attack

President Biden bows his head in a moment of silence Thursday as he speaks about the situation in Afghanistan from the White House's East Room. Drew Angerer/Getty Images hide caption

Police officers investigate the scene in Vienna on Tuesday, the day after at least one gunman went on a shooting spree in the city center before he was shot and killed by police. Ronald Zak/AP hide caption

A demonstrator carries an "I am Samuel" sign as people gather Sunday in Place de la République in Paris to pay tribute to slain history teacher Samuel Paty. Similar rallies took place in other French cities as the country reels from the attack. Bertrand Guay/AFP via Getty Images hide caption

Authorities in France say they've detained nine people in connection with the decapitation of a history teacher in a Paris suburb on Friday. The teacher had shown caricatures of the Prophet Muhammad to his class, authorities said. Michel Euler/AP hide caption

Suspects (left to right) Hassan Hussein Mustafa, Liban Abdullahi Omar, and Mohamed Ahmed Abdi standing in the dock during their appearance for their case at the Milimani court in Nairobi on Wednesday. Abdi and Mustafa were found guilty, while Omar was acquitted of charges. Simon Maina/AFP via Getty Images hide caption

Police officers run to take position around Iran's parliament building in Tehran after an assault by several attackers. Four attackers reportedly reached the building's interior, and an explosion was heard, although it was unclear whether it was a suicide bomb or a grenade. Ali Khara/AP hide caption

A body is covered with a thermal blanket after a shootout between Italian police and a man near a train station in Milan's Sesto San Giovanni neighborhood early Friday. Italy's interior minister said the man killed is "without a shadow of doubt" Anis Amri, the suspect in the Berlin Christmas market attack. Daniele Bennati/AP hide caption