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.

The shooting happened around 10:30 a.m. local time on Friday at The Owl Bar, according to the Montana Division of Criminal Investigation.

A chilling wave of gun violence struck the United States as mass shootings unfolded in Los Angeles and Montana within days of each other. In downtown LA, a party turned deadly when gunfire erupted around 1 a.