A customer and a gas station clerk thwarted a robber by wrestling him to the ground and locking him inside the store until police arrived Sunday.

About 6:30 p.m, a man in his 20s walked into Sinclair, 873 E. South Temple, and put a Red Bull energy drink and a note demanding money on the counter, said Salt Lake Police Lt. Brian Purvis.

The man claimed he had a gun, but the clerk refused to open the cash register. The suspect banged on the register, which opened it, and tried to grab the cash, Purvis said.

Police were called and originally believed there was a hostage situation inside the store. As it turned out, it was the robber being held hostage.

The clerk wrestled the robber to the ground with the help of a customer. Then the clerk locked the doors so the robber could not escape, police said.

"When officers arrived, he was standing with his hands up," Purvis said.

The man was arrested for investigation of robbery.

The suspect did not have a weapon on him, but police said the clerk's decision to fight him was "very risky."