FBI agents arrested 18-year-old Sheikhdoon Abdullahi Mohamud in Richfield, Minnesota, after he purchased an inoperable AK-47-style rifle, magazines, and ammunition from an undercover employee during a sting operation tied to an alleged ISIS-inspired plot.

Federal authorities have arrested an 18-year-old Minnesota man accused of planning a mass-casualty attack at the Mall of America in an alleged plot inspired by ISIS.

Sheikhdoon Abdullahi Mohamud was arrested Tuesday in Richfield, Minnesota, after investigators say he purchased an AK-47-style rifle, four magazines and 200 rounds of ammunition from an undercover FBI employee posing as an ISIS member. According to the criminal complaint, he paid $600 for the weapons and ammunition. 

Authorities said Mohamud had been under investigation for nearly two years. During that period, he allegedly communicated with a confidential FBI source and expressed an interest in joining ISIS overseas. When he determined that he could not afford to travel to Somalia, investigators say he shifted toward carrying out an attack in Minnesota. 

According to the indictment, Mohamud allegedly discussed targeting the Mall of America and planned the attack for October 24, when a Hmong arts celebration was scheduled to take place. Prosecutors say he told the confidential source that he wanted to kill dozens of people. 

U.S. Attorney Daniel Rosen said investigators were able to identify and disrupt the alleged plan before an attack could take place. He said Mohamud had expressed an intention to kill “maybe 30 to 60 people,” according to the allegations outlined in the criminal complaint. 

FBI Minneapolis Special Agent in Charge Christopher D. Dotson said Mohamud allegedly sought martyrdom while pursuing his plans to kill civilians. The investigation, authorities said, involved monitoring his communications and using an undercover operation to determine whether he would move forward with acquiring a weapon. 

Mohamud made his initial appearance in federal court in St. Paul on Wednesday. It was not immediately clear whether he had an attorney available to comment on the allegations. 

The charges remain allegations, and Mohamud is presumed innocent unless proven guilty in court.

The case comes as federal authorities continue to monitor individuals who express support for or seek to join designated terrorist organizations. Officials said the investigation demonstrates the importance of identifying potential threats before they develop into attacks on civilians.