It wasn’t immediately clear why police were involved in an altercation between an Iowa high school assistant coach and a referee, but now court documents have revealed additional details.

A high school football game in Iowa drew attention earlier this week for an incident between an assistant coach and a referee that caused the coach to resign and police to get involved.

It happened during the second quarter of a football game between Dowling Catholic High School and Lincoln High School at Valley Stadium on Friday, according to local TV station 13-WHO.

A non-call on what looked to be a targeting hit on a Lincoln’s quarterback caused Jason Storm, a 15-year assistant coach and father of the player, to erupt, and Storm confronted the referee.

Now KCRG is reporting that Storm, 44, a former assistant football coach at Lincoln High School, turned himself into the Polk County Jail Wednesday on a harassment charge. An arresting document shows Storm threatened the head official during Friday’s game against Dowling High School, saying he was going to “F—— kill him” due to a ‘no-call’ on a helmet-to-helmet hit against the Lincoln quarterback during the game against Dowling Catholic.

The court documents say Storm had to be restrained by other members of the coaching staff before being escorted out of the stadium. Storm apologized for his actions.

Des Moines School District officials said the referee should have made the call.

The video below is from 13-WHO: