A stretch of U.S. 89 in northern Arizona will remain closed indefinitely because of damage to the roadway about 25 miles south of Page, the Arizona Department of Transportation says.

Engineers are trying to determine what caused a 150-foot section of pavement to buckle. Transportation officials say the cause might be what it calls a "geologic event," and they said the repair work will have to be extensive.

Traffic is being detoured around the closure by using U.S. 160 and State Route 98. That adds 45 miles of driving.