CHADRON, Neb. (AP) — Authorities say a heart condition killed a 3-year-old boy found unconscious and not breathing in Chadron.

Dawes County Attorney Vance Haug said in a news release Thursday that Damion Neidert died of myocarditis, an inflammation of the heart muscle caused by a viral or bacterial condition.

More tests have been ordered to determine what led to his case of myocarditis.

Officers sent to the home around 11 a.m. Saturday couldn’t resuscitate the boy.