Boulder County sheriffs, SWAT teams and other area first responders were on-scene for an armed man who had barricaded himself in a vehicle on Flagstaff Road most of Monday.

At 10:26 a.m., Boulder County deputies received a call from two people in a parking lot, located near the 2100 block of Flagstaff Road, observing a man acting suspiciously and then heard a gunshot, according to a spokesperson from the Boulder County Sheriff’s Office.

Upon arrival, Boulder County deputies and the Boulder Police Department confirmed the suspect was armed with a handgun, but refused to leave his car with authorities there, the spokesperson said.

They blocked his car in and attempted to negotiate.

At 4:20 p.m., sheriff’s office officials reported they believe the man killed himself “despite hours of negotiation and exhaustive efforts to resolve the situation peacefully.”

Flagstaff Road remained closed between the base of Flagstaff and the 2200 block. Gross Dam Road will “only be accessible to local residents while Flagstaff Road is closed,” according to the sheriff’s office.

The scene remained active as deputies continued to investigate.

Boulder Open Space & Mountain Parks added that trails on Flagstaff Mountain are closed.