Cleveland Browns defensive end Myles Garrett will miss the remainder of the NFL season after being suspended indefinitely for his attack on Pittsburgh Steelers quarterback Mason Rudolph.
The two players were involved in a scuffle with just seconds remaining of the Browns' 21-7 victory over their AFC North rivals at the FirstEnergy Stadium on Thursday night.
During the melee, Garrett managed to rip the helmet off of Rudolph before using it "as a weapon", according to the NFL, by swinging it at him and striking him on his head.
A mass brawl between players from both sides then ensued, with Garrett joined by defensive tackle team-mate Larry Ogunjobi and Pittsburgh centre Maurkice Pouncey in being ejected from the game.
Pouncey, who threw punches at Garrett and attempted to kick him in the head while he was on the ground, has received a three-game ban.
A NFL statement read: "The Pittsburgh Steelers and Cleveland Browns organisations have each been fined $250,000 (£193,668) and three players – Cleveland's Myles Garrett and Larry Ogunjobi, and Pittsburgh's Maurkice Pouncey – have been suspended without pay for their actions in Thursday night's game.
"Garrett has been suspended without pay indefinitely – at a minimum for the remainder of the regular season and post-season – and must meet with the commissioner's office prior to a decision on his reinstatement. He was also fined an additional amount.
"Garrett violated unnecessary roughness and unsportsmanlike conduct rules, as well as fighting, removing the helmet of an opponent and using the helmet as a weapon.
"Pouncey has been suspended without pay for three games and fined an additional amount for fighting, including punching and kicking an opponent.
"Ogunjobi has been suspended without pay for one game and fined an additional amount for unnecessary roughness, specifically for shoving an opposing player to the ground during an altercation."
The NFL has confirmed "additional discipline" will be meted out to other players for their part in the altercation, including those "that left the bench to enter the fight area".
Garrett, Pouncey and Ogunjobi have three business days to appeal.
After the game, Garrett stated to NFL.com that he "made a mistake, I lost my cool and I regret it".
He added: "It's going to come back to hurt our team. I appreciate my team having my back but it should've never gotten to that point. It's on me.
"It was embarrassing. What I did was foolish and I shouldn't allow myself to slip like that. It was out of character, but it was a situation like that, it is an emotional game, and I allowed myself to follow through those emotions."
Garrett has since issued a sincere apology to all concerned via the Browns' Twitter feed, and has vowed to make amends.
Garrett said: "Last night, I made a terrible mistake. I lost my cool and what I did was selfish and unacceptable.
"I know that we are all responsible for our actions and I can only prove my true character through my actions moving forward.
"I want to apologise to Mason Rudolph, my teammates, our entire organisation, our fans and to the NFL.
"I know I have to be accountable for what happened, learn from my mistake and I fully intend to do so."
The Browns and Steelers meet again at Pittsburgh's Heinz Field on December 1.