A grandfather tripped up an armed man as he was being pursued by police, allowing officers to swoop in and arrest him.

The man known as "Bill", whose real name has not been identified by the police, was waiting for his granddaughter outside a library in Columbus, Ohio, when he heard police sirens.

As the suspect ran past him, he slid his leg backwards tripping him up. His gun flew out of his reach as he hit the ground.

“I could see that he was holding something in his waistband while he was running,” Bill said. “He was coming my way, so I got in his way to slow him down so you guys could get him.”

Columbus police said his quick thinking may have averted a shoot out with the man and "likely saved his life."

After the suspect was arrested, officers recovered a pistol and 29 rounds of ammunition from him.