Police said Shelell Freeman, 39, and an 8-year-old boy, whose name was not released, were in a Chevrolet Malibu that went into a retention pond next to a First Guarantee Bank on Youngerman Circle at Argyle Forest Boulevard about 8:40 a.m.
The woman was taken to Orange Park Medical Center and the boy to Shands-Jacksonville Medical Center. At mid-afternoon, both remained in critical condition.
Police told Channel 4's Jason Law was told that Freeman was in the drive-through ATM lane at the bank when she dropped something outside the car, opened her door and got out to retrieve it. When the car began moving forward, she jumped in to try and stop it, but hit the accelerator rather than the brake, officers said.
A witness told Channel 4's Jason Law that the driver was already out of the car when he got to the pond, but the child was under water for five to 10 minutes before he was found.
A witness stopped Thomas Southworth and asked if he could swim because there was a boy drowning in a pond.
"They said they were looking for the boy, so I jumped in right away." Southworth said.
Orvan Johns said he saw the car go into the water and ran to help. He said he also jumped into the water and opened the car door, but the child was not was inside, so he felt around with his hands and feet until he found the boy.
"We pulled him up on the bank and I gave him the CPR -- the mouth-to-mouth -- and he started spitting up a little water. And then we felt a little heartbeat and so I kept on and then he started spitting up more and he started breathing," Johns said. "I was just thankful the Lord gave me the the ability to do something like that."
A second witness said both the woman and child were alive when paramedics arrived.
"The pulses were faint, but they were breathing," Damien Pittmon said. "I was just praying to God he saved their life."
"I really didn't think he was going to make it, to be honest. But, luckily, once he started doing CPR, he came back," Southworth said. "All the things that go through your head -- you don't know the horrors that could have happened."
The police dive team searched the pond in case there were other victims, but officers said all the children in the family were accounted for.
Traffic homicide detectives were called to the scene since the injuries were life-threatening. While the investigation is in its preliminary stage, an officer said it did not appear the child was restrained by either a child safety seat or seat belt.
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