A man broke into the Colorado Supreme Court building overnight, firing several shots and briefly holding a security guard at gunpoint before being arrested, police in the western US state said Tuesday.

The Colorado State Patrol said it did not believe the incident was linked to the recent ruling by the high court barring ex-president Donald Trump from the state's 2024 presidential primary ballot.

The CSP said in a statement that the man, who was not identified, had been involved in a car crash nearby and had pointed a gun at the other driver.

He later shot out a window in the Denver building which houses the Colorado Supreme Court and held an unarmed security guard at gunpoint.

The man made his way to the seventh floor of the building where he fired additional gunshots, the CSP said.

He surrendered to police about two hours later without incident.

"There is significant and extensive damage to the building and the investigation is ongoing," the CSP said. "There are no injuries to building occupants, the suspect, or police personnel."

"At this time, it is believed that this is not associated with previous threats to the Colorado Supreme Court Justices," it added.

The CSC ruled last month that Trump, the frontrunner for the 2024 Republican presidential nomination, is ineligible for the US presidency because of his role in the 6 January 2021 attack on the US Capitol by his supporters.

The Colorado Republican Party has appealed the decision to the US Supreme Court.

The top election official in Maine has also blocked Trump from the Republican presidential primary ballot in the northeastern state.