LA VISTA, Neb. (AP) — The search for an autistic 11-year-old Nebraska boy who has been missing since last week continues to focus on a lake and surrounding park in the Omaha suburb of La Vista.

On Sunday, authorities lowered the lake at Walnut Creek Recreation Area by several feet to help searchers get a better view of what lies along the shore of the lake.

Debris in the lake, including tires and tree limbs, has hindered the water search for Ryan Larsen who has been missing since he walked out of his elementary school on May 17 during changes in morning classes in La Vista.