The victims have been identified as 41-year-old Pete Luciano and his son 13-year-old Jordan Luciano.
The incident happened before 3:00 p.m. Friday at Devil's Pool, a popular swimming area in the creek located a short distance from the Valley Green Inn in Fairmount Park.
The Philadelphia Police Marine Unit and firefighters worked frantically to save the pair.
But their search ended in a recovery, not a rescue.
"We believe it was in excess of 10 feet where they were located," Philadelphia Police Chief Inspector Joseph Sullivan said of the water's depth.
Luciano and his four children were enjoying a day along the creek when police say Jordan voluntarily went into the water to swim.
But he soon found himself under the surface.
"The depth, it changes very rapidly and very suddenly, and apparently that is what happened," said Sullivan.
But the tragedy only escalated from there.
The boy's father jumped in to rescue the boy but he found himself struggling.
His three younger children watched in horror along the banks of the creek.
"At that point the three other children that were here ran back to Valley Green Inn to notify the other adults that they needed assistance," said Sullivan. "911 was contacted."
Action News spoke with the wife and mother who says her son was out there at the beginning of the summer to swim in the Wissahickon and he could swim and so could her husband.
But Philadelphia Police say the creek was just too powerful.
Michelle Luciano of Hunting Park and the mother of 8, has been surrounded by her large family since her husband Pete and son Jordan drowned in the Wissahickon Creek.
Luciano and her husband were separated but he spent a lot of time with their children.
"I will always have the deepest love for him, respect to know that he risk his life to save our child," said Luciano.
Philadelphia Police say Jordan's brave younger brother Justin was the one who grabbed his siblings and ran for help.
"I know he's hurting but Justin has this tough interior," said Luciano.
Pete Luciano grew up in the Hunting Park community and he was a security guard.
Family members say what he did for his own son, he would have done for any child in trouble.
Annette Rodriguez, the victim's cousin said, "He thought about everyone in the neighborhood...he was a good man ."
Wissahickon Creek is a popular, scenic part of Fairmount Park. But police say the creek can be deceiving: shallow in spots but with sudden drops in depth.
And the current can pick up in spots, overpowering swimmers.
"Swimming is prohibited for a reason," said Sullivan. "It's not safe."
Funeral arrangements are still being planned for the father and son.