Action News has obtained cell phone video that apparently shows the heated argument.
Colwyn police say one of their own, Officer Clinton Kraddock, and Darby Police Chief Robert Smythe are the two men involved.
"After it's all said and done, as the sun goes down and the lights go out, we're all fellow officers, we're all police, we're all here to do a job, to back each other up, to make sure every officer gets home to see his or her family," Lt Wendell Reed of the Colwyn Police Department said.
Colwyn police say it began Friday when Kraddock was driving through neighboring Darby Borough and was flagged down. He responded and took one man into custody.
He called Darby for backup because it was their jurisdiction.
The argument unfolded and Kraddock alleges Chief Smythe slammed a car door on his leg and he was treated at a local hospital.
"He went to help that person that needed aid and for him to wind up in a hospital at the hands of another police officer, it's not a good thing," Colwyn Council President Tonnette Pray said.
Pray says there is a history of tension between the departments when it comes to backing up one another.
They have a mutual aid agreement and it has led to a feud between the departments.
"We share a common street, Main Street, and we share common areas, and in some parts of Colwyn, Darby does intersect and intertwine with us," Reed said.
Action News reached out to Chief Smythe, but our phone calls were not returned.