PARK HILLS, Mo. • A senior at Oakville High School was killed when he lost control of an ATV and crashed Monday in St. Joe State Park.

Aaron C. Hurst, 17, was pronounced dead at 12:20 p.m. Monday in an off-road area of the state park in Park Hills.

At about 11:45 a.m. Monday, Aaron and two friends were riding through sand flats in the state park. They had the day off school because of Presidents Day. Aaron was alone on a 2003 Honda Rancher, an all-terrain vehicle.

Aaron's vehicle went through water that was about four inches deep and hydroplaned, said St. Francis County Coroner Jim Coplin. Aaron lost control of the vehicle and it overturned, the Missouri Highway Patrol said.

Aaron's two friends were ahead and him and didn't see him crash. Once they realized he was down, they came back to him but were unable to help him, Coplin said. Aaron had suffered massive head injuries and died at the scene, Coplin said.

Even though Aaron was wearing a helmet, the helmet was not designed for the kind of riding he was doing, Coplin said.

Aaron's mother, Christine Schuler Hurst, said her son was a senior at Oakville High School and a good student who took part in the district's tutoring program, helping teach math skills and spelling to first graders through the A+ Schools Program. Aaron hoped to attend St. Louis Community College at Meramec and focus on electrical engineering.

Schuler Hurst said she learned from the coroner that he suspected the helmet her son was using wasn't heavy-duty enough for riding off-road vehicles like ATVs.

"We bought it at Walmart," she said. "We thought it was safe enough."

The St. Joe State Park in Park Hills is a 8,200-acre park with an off-road vehicle riding area. Schuler Hurst said he had gone to the park before to ride on the trails with friends the family had known for years.

Schuler Hurst said Aaron's father, Robert Hurst, is in the Missouri National Guard and was deployed to Iraq when Aaron was 9 years old and Kosovo when Aaron was 13.

"Aaron really pulled the family together when his father was gone," she said. "He was the cornerstone."

In addition to his parents, Aaron is survived by sisters Emily, 14, and Jillian, 11.

Aaron's parents were featured in the Post-Dispatch in August of 1993 when they got married in their Army fatigues in the area where they had been on sandbagging duty during the Great Flood of 1993.

When the paper did an update on the flood's aftermath two years later, the story featured a photo of the young couple along with 11-month-old Aaron.