A manhunt is intensifying for the gunman who allegedly killed a bartender and three patrons at a bar in southwestern Montana, authorities said. Michael Paul Brown allegedly opened fire around 10:30 a.m. local time Friday at The Owl Bar in Anaconda, a city of about 9,000 people in southwestern Montana, according to the Montana Department of Justice.

Local, state and federal officials were searching for a 45-year-old man who is believed to be armed and dangerous.

Officials urged residents to go about their weekend as the authorities searched the foothills for the veteran suspected of killing four people in the town of Anaconda.