Some alert hikers helped stop a man suspected of starting a brush fire in Runyon Canyon Sunday morning. 

Fashion designer Davanh DiMarco was hiking with her partner Scott Mitchell, a former University of Kentucky wide receiver, when she spotted a man coming out of the bushes seconds after the fire started.

"I'm like that's odd, but maybe he was just trying to go to the rugged terrain," DiMarco said. "Then, like 15 seconds later, the tree was on fire."

After connecting the dots, DiMarco shouted for people to stop the man as he tried to get away. 

"Guy's about 150 yards away. I had to track him down, run him down," Mitchell said. 

Mitchell and another hiker stopped the man from running away until park rangers arrived and arrested the suspected arsonist. 

"We feel the magnitude more now because we understand what it could have been," Mitchell said. 

The flames burned near the Sunset Fire scar, one of the several wildfires that threatened Los Angeles County homes in early January. Firefighters doused the fire with water drops and held it to less than an acre. 

Law enforcement has not identified the suspect. Prosecutors have not charged him as of Monday.