The department says Eads died Saturday night while on the scene of a fire call in Avenal.
Eads responded to a call on Skyline Boulevard near Central Avenue for reports of smoke inside a structure.
Officials say while on the scene, Eads suffered a medical emergency and was taken to a nearby hospital, where he died.
Eads started with Kings County in 2003 and was promoted to captain in 2021.
He worked for the county for more than 20 years.