Trump praises FBI for foiling ISIS-inspired mass shooting plot. US President Donald Trump said the FBI "did a great job" after they arrested 18-year-old Sheikhdoon Mohamud for allegedly planning an ISIS-inspired mass shooting. Authorities said Mohamud pledged allegiance to ISIS and planned to kill 30-60 people at Minnesota's Mall of America. He was arrested after he bought an AK-47 and 200 rounds of ammunition from an undercover FBI agent.