The three had anchored a boat near Mandarin Point in Jacksonville, Florida, in the St. Johns River. Steven was going to take his two sons to swim nearby and do some fishing.
After swimming for almost an hour, Chase Poust reached a nearby house and called for help.
However, Steven was unaware of the strength of the current, and soon after, seven-year-old Chase saw that Abigail, who was wearing a life jacket, had been swept from the boat.
Although he was not wearing a life jacket, Chase left the boat to try to save his sister. Steven also dived into the water in the hope of catching his daughter, but she continued to float.
Steven told News4Jax: ‘I told them I loved her because I wasn’t sure what was going to happen.
I tried to keep both of them. I got exhausted. She walked away from me.
Video: Seven-year-old boy is hailed as a hero after swimming for an hour to call for help