With the death last week of an 11-year-old Minnesota boy, there are now at least 14 children with autism known to have died in the U.S. this year after slipping away from their caregivers.

The tragic phenomenon goes by various names – wandering, elopement, bolting – and about half of autistic children are prone to it.

Advocacy groups say wandering has led to the deaths of more than 60 children in the past four years. They are working to raise awareness and find more effective preventive measures.

All but one of this year’s victims drowned, evidence of a fascination that many autistic children have with water. The body of the latest victim, Anthony Kuznia, was found Thursday in the Red River near his home in East Grand Forks, Minn.