An 18-year-old man accused of telling an FBI informant he wanted to attack the Mall of America during the Hmong Arts Celebration on Oct. 24 was arrested at gunpoint Tuesday in Richfield, Minnesota, during an arranged meeting to buy an AK-47-style rifle for $600, according to a federal criminal complaint filed Wednesday. In the complaint, authorities say a "confidential human source" exchanged "hundreds of bi-directional messages through multiple social media and encrypted messaging applications" with Sheikhdoon Abdullahi Mohamud from December 2024 until Tuesday. In those exchanges, Mohamud allegedly "expressed his desire to travel to Somalia" to join al-Shabaab and "fight...