A California prosecutor is pursuing criminal charges against parents of children involved in e-bike crashes.

Orange County District Attorney Todd Spitzer has more than two dozen open investigations.

His office has already charged four parents, including the mother of a 14-year-old accused of killing a pedestrian.

Other areas are taking different steps.

New York City warned online retailers about selling illegal e-bikes after a 17-year-old died.

New Jersey now requires riders to be at least 15 and have a license.

California has no minimum age for lower-powered bikes.

Some parents and advocates say the measures miss the mark.

Monica Stafford, whose daughter fractured her skull, called for a unified national set of rules.

She said officials are in a "Wild West of laws."

Cycling groups argue that many dangerous vehicles are actually e-motorcycles falsely marketed as e-bikes.

Researchers stress that injuries from e-bikes are more severe than from regular bicycles.

Dr. John Austin said patients tend to be younger and unhelmeted.

Parents like Sharon Franke say safety starts at home, with research and training.

She said balancing fun and safety is "overwhelming right now."