He attempted to fight off the attackers by throwing a bicycle at them, which caused one of them to run at him with a machete.
The terrorist began to chase him but changed his mind and headed back towards Borough markets.
It was only later that Gowls discovered Sara was one of the eight victims in the terror attack.
"To Sara's family, I just want to say I am so very sorry for their loss. I really tried to help her and get them to chase me," he said.
Two Australians have been confirmed dead from the attack, including Sara, and nurse Kristy Bode, who ran towards the danger in an effort to help those injured.
This article originally appeared on New Idea