QUAKERTOWN, Pennsylvania (AP) — A man drowned after rescuing two children who got into trouble while swimming at an eastern Pennsylvania state park, authorities said.

The Bucks County coroner’s office said Marvin Alexan Fernandez Chicas, 37, “disappeared in the water” after rescuing the children who were swimming at Nockamixon State Park on Thursday evening.

The coroner’s office said Friday that the cause of his death had been confirmed as drowning following an autopsy and the manner of death appeared to be accidental. Coroner Meredith Buck said in a statement that the office is extending “its deepest condolences” to his family.

Wesley Robinson, spokesperson for the Department of Conservation and Natural Resources, said the two children were seen struggling in the Tohickon Creek in the cliffs area at about 5 p.m. Thursday. Chicas went in and got the children to shore, then began to struggle, Robinson said. His body was found by divers in the lake more than two hours later.

Swimming is prohibited in the creek and in the 1,450-acre Lake Nockamixon, the largest in the county, Robinson said.

Fire Chief Harry Grim of Haycock Township, who said about 10 divers were involved in the search, told WFMZ-TV that many parts of the lake are deceptive and dangerous.

“Unfortunately, people don’t follow the rules, and the sad reality is it’s not a smooth, gradual slope under the water, and they step off into a deep area, they take a gulp of water, and they die unfortunately. It shouldn’t happen, but it does,” Grim said.