A brush fire burned about 40 acres in one hour yesterday in the San Timoteo Canyon. CalFire official say the blaze was at 2 acres jts after 3:3o pm at San Timoteo Canyon Road and Redlands Boulevard, North of Moreno Valley. By about 4:30 it had grown to 40 acres. Officials say no structures in the area were threatened. About 75 firefighters were on the scene. One fire fighter was treated for a minor-heat related injury. The 100-plus degree temperatures in the area did not help the efforts of fire crews.