A routine traffic stop in Dayton almost turned tragic.

An officer pulled over a car because it had a missing headlight. He says the driver became uncooperative and started to fight.

During the almost five minute long struggle, investigators say the driver tried to grab the officer's gun and taser several times.

Police backup was on its way, but a passerby got on scene first. She started hitting the driver in the back of the head, allowing the officer to regain control and other officers to arrive and help him.

"I think it's very commendable," said Dayton police officer Larry Tolpin. "Although, don't get me wrong, I'm not endorsing that citizens participate in this manner. But, under this particular circumstance, it was very commendable of her."

The driver was arrested. The Good Samaritan has not been identified.