Authorities are searching for 45-year-old military veteran Michael Paul Brown who killed four people at a Montana bar on Aug. 1.

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.

A manhunt for Michael Paul Brown has been underway since Friday morning, when four people were shot and killed in the town of Anaconda.