Three hours later, rescuers with the Lewisville Fire Department's dive team pulled Mitchell’s body from water that was about 6 feet deep, the Morning News reported.
Mitchell's heroic act at the lake was typical of his character, Herrera told the Star-Telegram.
"He was in the process of enrolling in college to become a firefighter. He wanted to be a firefighter because he wanted to save lives. Running in when everyone is running out. He wanted to be a hero, not just once but every chance he could," Herrera told the newspaper. "Shortly put, he was an amazing man and I am lucky to have known him."
Mitchell’s mother, Stacy Thompson, said she was puzzled that her son drowned.
"Being in the Army and all that, he could swim like a fish. That's why I can't understand what happened," Thompson told the Star-Telegram.
Herrera said she and Mitchell had set a wedding date before heading to the park, the Star-Telegram reported. They had one child together, 1-year-old Bryson, and were planning to combine families with Keira and Mitchell’s two children, Paris and Trenton Mitchell, the Star-Telegram reported.
Mitchell’s Instagram profile included the hashtags #proudfather and #soldier, and his Facebook page focused on his love for the Dallas Cowboys and snakes, the Morning News reported.
"He was an amazing father," Herrera told the Star-Telegram. "He was loved and will be missed. No matter what, he was a hero."