A North Dakota man is accused of threatening to kill former President Barack Obama, breaking into a National Park Service historic site and threatening other people.

A federal grand jury indictment filed Wednesday levies felony charges of burglary, damage to property of the U.S., terrorizing, malicious mischief, threatening to kill a former U.S. president and three counts of threatening interstate communications against Ian Patrick Stewart of Williston.

The indictment said Stewart "did knowingly and willfully threaten to kill and inflict bodily harm upon" Obama between April 20 and May 13. The document doesn't detail the alleged threat. Stewart also is accused of threatening to injure three Williston residents in May.

The court papers say Stewart entered Fort Union Trading Post National Historic Site on May 13 when it wasn't open to the public, caused a building to evacuate and threatened a Park Service employee and Williams County law enforcement. He was armed, according to the indictment.

Several law enforcement agencies responded, and the historic site and the road to it were closed during the "barricaded subject situation," the Williams County Sheriff's Office previously said.

Stewart is held at the Ward County Detention Center in Minot. He is scheduled to appear Monday in court. No attorney is listed for him in court records. The Associated Press left him a voicemail.

Fort Union Trading Post National Historic Site is along the Missouri River at the Montana-North Dakota border. The site focuses on the history of the fur trade and the post that operated there for decades in the 19th century.