Craig Robertson, a Utah man who has made violent threats against U.S. President Joe Biden and other Democratic officials, has been shot dead by FBI agents on Wednesday.

The FBI said the incident began when special agents attempted to serve arrest and search warrants at Robertson's home in Provo, south of Salt Lake City. The shooting happened at 6:15 a.m., hours before Biden was scheduled to land in Utah on Wednesday.

Robertson has called for the assassination of Biden and U.S. Vice President Kamala Harris in September 2022. Referring to himself as a "MAGA Trumper," a reference to former President Donald Trump's "Make America Great Again" slogan, he also posted threats against top law enforcement officials overseeing court cases against Trump.

Robertson was charged under seal on Tuesday with three felony counts, including making threats against the president and against FBI agents investigating him, court documents show. Investigators said Robertson appears to own a sniper rifle and other firearms.

He posted online on Monday that he had heard Biden was coming to Utah and he was planning to dig out a camouflage suit and begin "cleaning the dust off the M24 sniper rifle."

Neighbors described Robertson as a frail, elderly man who walked with the aid of a hand-carved stick, AP reported. They said he didn't seem a threat though he regularly carried guns.

The shooting is under review by the FBI and no further details were released.

Biden is expected to visit Salt Lake City on Thursday to talk about the PACT Act, which expanded veterans' benefits.

(With input from agencies)