Firefighters arrive at a security perimeter set in the Rue de la Loi near the Maalbeek - Maelbeek subway station, in Brussels, on March 22, 2016, after an explosion killed around 10 people, according to spokesman of Brussels' fire brigade A string of explosions rocked Brussels airport and a city metro station on Tuesday, killing at least 13 people, according to media reports, as Belgium raised its terror threat to the maximum level. / AFP / Belga / LAURIE DIEFFEMBACQ / Belgium OUT (Photo credit should read LAURIE DIEFFEMBACQ/AFP/Getty Images)
