RIVERSIDE, Calif. - Two children were killed in separate skateboarding accidents this month in Riverside County, prompting safety experts to urge skaters to wear safety gear and ride in designated areas.

Twelve-year-old Sean Mikhail died Aug. 11 in Moreno Valley when he fell off his skateboard and hit his head on the pavement. He was not wearing a helmet.

In Menifee, Marlena Mattfeld, 11, of Long Beach, died Aug. 13, three days after she lost control and slid beneath a moving motor home, near her grandmother's home.

While skateboarding deaths are uncommon, they are a reminder of the importance of taking precautions like wearing a helmet, said Victoria Young, program coordinator for Riverside County Injury Prevention Services.

California law requires anyone under 18 to wear a helmet while using any wheeled equipment, including skateboards, bicycles and scooters. Many cities have ordinances that regulate skateboarding and helmet laws at city parks and on public property.