Gas prices continue to fall in Arizona. Triple-A Arizona says gas prices are down a cent from last week to $2.91 a gallon. In Flagstaff, gas is down nearly two cents from last week to $2.86 a gallon. Some stations are selling gas for $2.69 a gallon. In Prescott, is also down nearly two cents a gallon to $2.99 a gallon on average. Some stations are selling gas for $2.84 a gallon and lower. Officials say increased supply with high demand is driving prices lower at the pump.