Experts on mass shootings said it’s rare for the gunmen who carry out such crimes to elude the authorities for so long.

Officers are "unrelenting in their pursuit, working around the clock" to find him, Montana Gov. Greg Gianforte stressed at a news conference on Tuesday. "Rest assured, our brave men and women of law enforcement aren’t giving up."

Police are looking for Michael Paul Brown, 45, after four people were shot and killed in The Owl Bar in the small town of Anaconda, Montana.