Firefighters are still working to suppress a 200-acre grass fire near Gunsight Pass that was reported Tuesday, authorities said.

The fire, located 15 miles east of Green Valley, in the Santa Rita Mountains, is now 50 percent contained, said U.S. Forest Service spokeswoman, D. Giselle Koehn.

Authorities have determined that the fire was human caused.

A helicopter is currently assisting the four hand crews, four engines and other fire support that are actively fighting the fire.

The forest service is optimistic that the crews will continue to make good progress today, Koehn said.

One hundred firefighters from Arizona State Forestry, Tubac Fire Department, Sonoita Fire Department, Green Valley Fire Department and the Coronado National Forest will continue suppression efforts today.

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At this point, no structures are currently threatened. The fire is under investigation.

The  company planning to build the Rosemont Mine recently closed public access to private roads leading to Gunsight Pass and to public land in the Santa Rita Mountains.

Contact reporter Caitlin Schmidt at cschmidt@tucson.com or 573-4191. On Twitter: @caitlincschmidt