UPDATE, 7:22 p.m.:
Casper Police Dept. Lt. Jeremy Tremmel tells K2 Radio News that the building was a detached garage. Authorities were initially called at 6:55 p.m. Friday. No injuries have been reported.
A cause has not yet been determined.
K2 Radio News is awaiting further details from Casper Fire-EMS.
The original story follows.
Casper firefighters are currently fighting a heavily involved structure fire in the 2000 block of South Melrose.
Roads in the area are currently blocked off and the public is strongly urged to stay away.
This is a developing story. Check back with K2 Radio News for updates.