PROVO — Some folks who parked illegally in American Fork Canyon last Saturday found their cars were missing when they returned.

The U.S. Forest Service, after handing out warning notices, towed away 16 vehicles. Parking enforcement will continue, Uinta National Forest spokeswoman Loyal Clark said.

"We tried giving warnings," she said. "It's not working."

Parking violations are more common on Saturday and regulations are particularly disregarded at the Aspen Grove and Timpooneke trailheads and Tibble Fork day-use site.

"On weekends, these extremely popular destination sites are filled to beyond capacity and recreationists are parking along the Alpine Loop, state Route 92. This situation is creating a hazard for those traveling the route," she said.

Parking areas at the trailheads are clearly marked. Forest Service rangers will close parking areas after they are full and motorists who park illegally outside designated parking areas, including turnouts, will be towed, Clark said.