The Chattahoochee River has claimed a third life from the family that lost a mother and infant Sunday near Columbus' Rigdon Park.

Three-year-old David Brown died about 1 p.m. Wednesday at Egleston Children's Hospital in Atlanta, where he was transferred from The Medical Center in Columbus after being pulled from the river Sunday afternoon, said Muscogee Coroner Bill Thrower.

Thrower said Wednesday that he had not been told the boy's cause of death, but likely it resulted from the oxygen deprivation he endured while in the river.

The boy's venturing into the water caused his mother to go in after him while holding his 11-month-old brother, police said. Both 30-year-old Krystal Ann Brown and her baby, Mister Brown, drowned.

They had been on a family fishing trip with the boys' father, who could not swim, but sent others to get help, police said. Officers arriving at the scene could not find the mother and two sons. Rescue divers recovered the two bodies and rushed the older son to the hospital.

The area has been the site of other drownings. The river cuts close to the Chattahoochee Riverwalk near Rigdon Park, and people there are often tempted to venture out. But the shallows end abruptly in a drop of about 15 feet, authorities said.

Assistant Chief Robert Futrell of the Columbus Department of Fire and Emergency Medical Services said rescue workers discourage pedestrians' taking such risks along the riverbank.

"It can go from 2 feet to 15 feet in one step," Futrell said. "And if the water's muddy, you can't see where that happens."

Thrower said Columbus also has had a drowning in the wetlands area east of the river. "It's just as dangerous as the river, if you don't know what you're doing or where you're walking," he said.