Salt Lake City, Utah - During a raid on Wednesday morning, FBI agents fatally shot a man in Utah who was under investigation for threats against Joe Biden, just hours before the president's visit to the state.

FBI agents attempted to enter the home of Craig Deleeuw Robertson in in Provo, just south of Salt Lake City, around 6:15 AM, according to a statement by the FBI in the AP.

Robertson posted online Monday that he heard Biden was coming to Utah and he was planning to dig out his camouflage suit and "clean the dust off" his sniper rifle.

The investigation began in April, and the Secret Service was alerted in June, anonymous officials told ABC News. Investigators determined the man's threats of physical harm were credible.

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In past Facebook posts, Robertson reportedly referenced a "presidential assassination" and made threats against Vice President Kamala Harris, Manhattan District Attorney Alvin Bragg, US Attorney General Merrick Garland, and New York Attorney General Letitia James.

A complaint filed by federal prosecutors in Utah said Robertson, who was in his early 70s, described himself as a "MAGA Trumper." He showed off his extensive collection of guns in online posts, including a semi-automatic rifle he called a "Democrat eradicator."

An FBI spokesperson told KSL of Wednesday's events: "The incident began when special agents attempted to serve arrest and search warrants at a residence. The subject is deceased."

"The FBI takes all shooting incidents involving our agents or task force members seriously," they added.

Biden is currently on a trip to the Western US, having spent Tuesday in the Grand Canyon, with plans to fly to Utah later on Wednesday.