Turn your sound on before watching this vid. These guys sound incredible!
From NBC Bay Area:
In the video, Samoa Crew 61, better known as the "singing crew," is seen walking down off the mountain in Shasta-Trinity National Park and signing acapella while other firefighters sang harmony.
Less than a month after this video was posted, this same crew of firefighters performed the Manu Siva Tau while battling Northern California's Gasquet Fire.