A 10-year-old South Carolina boy died last weekend several hours after he swallowed water in a swimming pool.
Goose Creek police say Johnny Jackson swallowed some water while swimming in a pool at his apartment complex around noon Sunday.
Police say he later complained he was tired and took a nap. When someone checked on him, water was coming out of his nose and he was having trouble breathing.
The boy later died at Trident Hospital.
Berkeley County Coroner Glenn Rhoad told the Charlestown Post and Courier of Charleston the boy's lungs were filled with water and he died of asphyxiation.
Rhoad said there was nothing suspicious about the death.
The boy, a fourth-grader called "Jon-Jon" by his family, essentially drown, medical experts told the Post and Courier.
Not all drowning deaths happen immediately. Other phenomena, such as secondary drowning, can occur as much as 72 hours later and without any warning signs.
Dr. Nelson Rosen, director of the trauma center a Schneider Children’s Hospital on Long Island, said secondary drowning is scary because there is a latent period where the victim looks as though they are fine.
"Any choking episode could be concerning," Rosen told FOXNews.com. "The only question is this: Everybody’s had a mouth full of water and choked, how do you know whether it will cause secondary drowning? I would say that if there is a significant episode to the point where people are concerned about the child’s well-being, then that should be investigated."
Rosen said parents should be on the look out for symptoms of respiratory or breathing problems, coughing and a "raspy" voice, as these could be indicative of injury to the lungs.
Although secondary drowning is a concern, it amounts to only 5 percent of total drownings, Rosen said.
"These are episodes that are not unheard of by any meaning, but even regular drownings are a relatively rare event in modern society," he said. "But I would still caution that any significant event be checked out in an emergency room. And if people now have a low threshold for these types of things, I would say that's fine. Better to err on the side of caution."
FOXNews.com health editor Marrecca Fiore contributed to this report.