Coaches and officials ran in during the chaos to separate the teams as the players were rushed off the floor.
A police officer was present at the game but the player who launched the attack was not arrested at the time.
It has now emerged that police have taken action.
Police charged the alleged attacker, 17-year-old Carter Prenosil, with wilful injury – causing serious injury — and held him in police custody. He has since been released on bail, Fox News reports.
"It was determined through the initial investigation that a player of the Carlisle Community School District, without provocation, struck a player of the Nevada Community School District team at the end of the game," the department said in a statement.
The statement from the Carlisle Police Department updated the condition of the alleged victim, Ty Dittmer, after preliminary reports he was recovering without serious injury.
"The victim sustained a loss of consciousness, injuries to his mouth and immediately received medical care," the statement claimed.
A spokesperson for the Iowa High School Athletic Association told local TV station WOI-DT: "Violent conduct has no place in Iowa high school activities.
"IHSAA administrators are working with both schools to ensure appropriate guidelines are followed for violent behaviours from student-athletes."
The viral video also shows one person can be heard yelling "Go, go" to the Wildcats as they ran from the floor.
While there are several versions of the video, one had more than 3.1 million views on Twitter on Thursday night (AEDT).
TMZ Sports earlier reported that police were looking into the video, but Nevada superintendent Dr Steve Gray told the website at the time it was well handled by those on the court.
"It's a very unfortunate situation," he said. "I'm happy they de-escalated it. I thought our coaches and staff handled it well and got everyone out of there without it worsening.
"This is without question an unfortunate incident that is not representative of the school culture that exists in Carlisle Community School District.
"I want to make it clear that this type of conduct is not tolerated at Carlisle CSD. The district will follow the student code of conduct policy and procedures throughout the investigation of this incident and implement appropriate consequences.
"All proper authorities have been notified of the incident."
But social media was quick to slam the incident.
Some slammed the boy who threw the punch and called for him to be rubbed out for the rest of the year, if not worse.
It's far from the first violent incident like this.
Earlier this month, former NBA star Corey Benjamin apologised after his daughter sucker punched and concussed an opponent.
"This is not how I raised my daughter," Benjamin, who played three seasons with the Chicago Bulls and one with the Atlanta Hawks, told NBC Los Angeles. In the video, Benjamin's daughter missed a shot. With her team down double-digits, she sucker-punched 15-year-old Lauryn Ham, a player on the other team.
