By The Associated Press

Crews are trying to contain a wildfire that broke out in central Arizona over the weekend.

Tonto National Forest spokesman David Albo says firefighters were working Monday on establishing containment lines around a 960-acre fire.

Albo says the blaze, which is about four miles south of Superior, is not threatening any structures. He says high temperatures and low humidity will make controlling the fire a challenge.

The fire started Sunday on a service road just off of Highway 177, about 65 miles east of Phoenix. Transportation officials have closed the highway in Pinal County.

The cause of the fire is under investigation.

Meanwhile, officials say crews have stopped movement of the Ajax Fire, a human-caused fire that has burned at least 40 acres 2 miles southwest of Arivaca.