A fire that has already burned 600 acres in Mexico, has now crossed into the United States in Rio Rico.
Fire crews are battling the Triple 2 fire in the Coronado National Forest. So far, it is only estimated to have burned about 50 acres in the U.S.
The U.S. Forest Service says the fire is human caused, but the way it was started is unknown.
No structures are threatened at this time.
"But the concern is that we don't want it to move too much further into this country on the Coronado," said Gerry Perry, Public Information Officer for Coronado National Forest. "[It] could get to a different kind of fuel source, could get to a different location that either complicates or improves the opportunities to address the fire."
Smoke and flames may be visible from Rio Rico and Nogales.
"It just depends on the direction of the wind and the velocity of the wind whether or not folks will be seeing smoke and flames. It's encouraging at this point that we're not seeing an awful lot of smoke coming off of it," said Perry.
Visitors should be aware that heavy truck traffic and helicopters flying to and from Pena Blanca Lake may be encountered along Ruby Road and in the immediate area.