1 Samuel 4:10-11, 18

So the Philistines fought; Israel was defeated and every man fled to his tent. It was a very great defeat, for thirty thousand foot soldiers of Israel fell. Also the ark of God was taken; and the two sons of Eli, Hophni and Phinehas, were killed. [1 Sam 2:34]

When he mentioned the ark of God, Eli fell off the seat backwards by the side of the [city] gate. His neck was broken and he died, for he was old and heavy. He had judged Israel for forty years.