Montana authorities are expanding a rugged, multi-agency manhunt for a former soldier accused of gunning down four people at a local bar, warning the suspect may be armed with camping gear and survival supplies stolen from a second vehicle.

The Montana Department of Justice revealed Sunday that Michael Paul Brown, 45, fled the Owl Bar shooting Friday night shirtless and barefoot, only to later be seen near a stolen white Ford F-150 loaded with clothing, food and outdoor gear.

“We know Michael Paul Brown was shirtless and barefoot when he fled…,” Montana Attorney General Austin Knudsen said on Sunday. “We have very good reason to believe that he is clothed now and possibly carrying camping gear. He is probably able to get around undetected.”

Brown remained at large as of Monday, with the manhunt carrying on over the weekend.

The U.S. Marshals Service is offering a reward of $7,500 for any information that leads to the arrest or capture of Brown. Residents are encouraged to call 1-877-926-8332 to report a tip. 

Residents in the area have been told to stay inside their homes and remain on high alert. He has been described as 5-foot, 10-inches and about 170 pounds, with blue eyes and brown hair.

The state’s attorney general told residents to not approach the armed and dangerous murder suspect, saying, “This is an unstable individual who walked in and murdered four people in cold blood for no reason whatsoever.”

Michael Paul Brown is wanted in connection to a shooting incident in Anaconda-Deer Lodge County, Montana. (Anaconda-Deer Lodge County Law Enforcement Center)

Brown was an armor crewman in the Army from January 2001 to May 2005 and served in the National Guard from April 2006 to March 2008, Army Public Affairs confirmed to Fox News Digital. He deployed to Iraq from February 2004 to March 2005 and left the service with the rank of sergeant.

He also served as an armor crewman in the Montana National Guard from April 2006 to March 2009, officials said.