The rescue happened near Bear Creek Park, close to the Barker Cypress and Morton Road nature trails.
Around 6pm, two 19-year-old men were fishing there when firefighters say it started raining and the water began to rise. That's when the men lost track of their trail and became disoriented.
The men decided to climb into a tree to avoid the rising water. They called 911 and stayed on the phone with emergency responders until a Houston Police Department helicopter was able to spot them.
Emergency responders were able to lower boats down on a fire truck ladder and cut through the brush.
"I think it's a last resort at that point. I think when water starts rising, what else are you going to do?" said HFD Capt. Ruy Lozano. "What we recommend is during these times, when you're getting flash floods, you shouldn't even be out here. It's too dangerous. It's too unpredictable."
Crews had Highway 6 closed as they worked the rescue.
Emergency crews say this rescue was a tough one. It took a couple of hours and when the firefighters came out of the water, they were covered in mud and were simply exhausted.
Both men who had been trapped were checked out on the scene but declined further medical attention.