TUCSON, Ariz. — Firefighters are using closed roads and natural barriers as they prepare lines to try to block the spread of a wildfire burning in mountains and hills overlooking Tucson.

The fire has burned 22 square miles (57 sq. kilometers) of grass, brush and trees in the Santa Catalina Mountains and near Redington Pass as of Tuesday.

Officials say aerial tankers are being used to delay the fire’s spread but that high afternoon temperatures likely will ground aircraft at times. Hot and dry weather is expected to continue for the near future.

The Mount Lemmon Highway and a 12-mile stretch of Redington Pass Road are closed because of the fire, and the small community of Summerhaven on Mount Lemmon has been evacuated.

The fire started Thursday. Its cause is under investigation.