Police have found the getaway car of a US military veteran who walked into a bar in the western state of Montana on Friday morning and fatally shot four people, but the gunman remains at large.

The shooting happened at The Owl Bar in the city of Anaconda at around 10:30 local time, the Montana Division of Criminal Investigation said. The bar owner told AP news agency he thinks the suspect just “snapped”.

Police said they have found the white Ford-150 pick-up truck that the suspect used to flee the scene, but no sign of the gunman.

Authorities are now focusing their search in a mountainous area west of Anaconda, and have asked residents in the area to stay home and lock their doors.

The Anaconda-Deer Lodge County Law Enforcement Center named the suspect as Michael Paul Brown in a social media post, adding he is “believed to be armed and dangerous”.

According to public records, he lived next door to the bar.

The owner of The Owl Bar, David Gwerder, who was not there at the time of the shooting, told the Associated Press: “He knew everybody that was in that bar.

“I guarantee you that. He didn’t have any running dispute with any of them. I just think he snapped.”

The suspect is a veteran of the US Armed Forces, a spokeswoman for the Army told US media. Lt Col Ruth Catsro said Mr Brown served as an armour crewman from 2001-05, and was deployed to Iraq from 2004-05.

“If seen do not approach,” the Anaconda-Deer Lodge County Law Enforcement Center said of the suspect. “Contact 911 for any way to contact Michael Paul Brown.”

At the time of the incident, the US Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said it was “responding to a shooting where multiple parties have been shot at a business in Anaconda”.

In an update on Friday evening, police said the victims had been identified, but their names would not be released until their families were notified.

Kelly DeRieux, a barmaid at Jodi’s Cantina and Sports Bar three blocks away from The Owl Bar, told BBC News over the phone that many businesses in town had shut down for the day.

A friend told her that heavily armed police came to her home, and “asked them to please say away from windows and lock their doors”.

Her restaurant remains open for now. “We have emergency precautions, if needed,” she said.

The Granite County Sheriff’s Office, which is nearby to Anaconda, posted on social media that the gunman was “said to be wearing a tye-dyed shirt, blue jeans and a orange bandana”.

The sheriff’s office added that the gunman’s home in Anaconda had been searched, and “cleared by SWAT” teams.

Anaconda is a former copper smelting hub, with a population of almost 10,000 people in south-western Montana, 109 miles (175km) west of Bozeman.

Montana Governor Greg Gianforte said he was monitoring the response to the incident.

“Please join Susan and me in praying for the victims, their loved ones, and the brave law enforcement officers responding to this tragedy,” the governor said on social media referring to his wife, Susan Gianforte.

The FBI was also at the scene helping in the investigation.

Montana Senator Steve Daines told local media that the “massive manhunt” was being aided by police drones.

The Owl Bar was built in 1893 to serve Anaconda’s copper workers, according to a 1987 article in the Montana Standard newspaper. It’s located in a neighbourhood of Anaconda called Goosetown.