A clerk in North Carolina took matters into his own hands when a would-be robber brandished a gun and demanded money.

Derek Mothershead, 26, was already on high alert because the We Buy Gold store in Hendersonville had been recently robbed.

Instead of handing over the cash, Mothershead gave the alleged robber, 25-year-old Mostafa Kamel Hendi, a left hook that knocked him out cold.

"When he came through the door he told me had a gun and he even flashed it," Mothershead told WYFF. "I stood up and threw my hands up and said, 'Take the money.'"

"I got the money and he had the bag out and instead of putting it in the bag I stuck it out and said, 'Just take it.' So, when he reached out, I took a step in, I cocked back and preloaded and I hit him hard," he recalled.

The punch knocked the would-be robber out cold and Mothershead was able to quickly grab the gun, which turned out to be a pellet gun.

"He kind of begged me, begged me to let him go," Mothershead explained. "I said, 'You came in and tried to rob us. You’re going to jail.'"

Watch this video from ABC's Good Morning America, broadcast Dec. 26, 2011.