JUST IN: FBI agents have arrested 18-year-old Sheikhdoon Abdullahi Mohamud for allegedly planning a mass shooting at the Mall of America in support of ISIS. @​Garrett FoxNews reports that federal investigators are saying Mohamud pledged allegiance to ISIS and discussed targeting a crowded event at the mall, allegedly telling a confidential source he could "drive straight to the crowded place and start shooting." The FBI moved in after Mohamud allegedly paid $600 to an undercover employee for an inoperable AK-47-style rifle, four magazines, and roughly 200 rounds of live ammunition, with a full investigation still ongoing. ▻