Authorities say there are signs Michael Paul Brown has been in a mountainous area since he allegedly shot and killed four people in an Anaconda bar on Friday.

Stymied by treacherous terrain and untamed wilderness, authorities are struggling to find an Army veteran suspected of killing four people at a Montana bar. But the difficult landscape isn’t the only challenge.

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.