PLYMOUTH — A Twin Cities park district is testing out tracking devices to locate lost visitors in an effort to protect vulnerable guests.

The Three Rivers Park District police chief said the devices will help track visitors at risk of wandering away, such as people with autism or Alzheimer’s disease.

The district is leasing four gadgets that include wearable tracking units. They sound an alarm if a wearer walks too far from a caregiver and include a GPS that can pinpoint the wearer’s location.

The police chief said park officials responded to about 57 missing persons reports last year. He said each case was quickly resolved.

There have been several cases across the country of children with autism wandering away from caregivers over the past year.