CLEVELAND (AP) — Myles Garrett swung a helmet. The NFL swung back.

The Browns star defensive end was suspended indefinitely — at minimum, the rest of the regular season and the playoffs — on Friday for his violent outburst Thursday night, when he ripped off Pittsburgh quarterback Mason Rudolph’s helmet and clubbed him on the head with it during the final seconds of Cleveland’s 21-7 win.

The league said Garrett “violated unnecessary roughness and unsportsmanlike conduct rules, as well as fighting and removing an opponent’s helmet and using it as a weapon.”

In a statement released Friday by the Browns, the former No. 1 overall pick 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 apologize to Mason Rudolph, my teammates, our entire organization, 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.”

In addition, Browns defensive tackle Larry Ogunjobi was suspended one game, and Steelers center Maurkice Pouncey was suspended three games. And the Steelers and Browns organizations each were fined $250,000.

The NFL also mandated that Garrett must meet with the commissioner’s office before any decision is made on his reinstatement.

The NFL acted swiftly to punish Garrett, whose actions brought reaction from players across the league.

Kansas City Chiefs quarterback Patrick Mahomes posted “Bro I can’t believe that just happened” on Twitter following the game and Houston defensive end J.J. Watt wrote: “That. Is. Insanity. Wow.”

After pulling Rudolph down with eight seconds to go following a short pass, Garrett wrestled with Pittsburgh’s QB on the ground with both players grabbing each other’s heads. When they got to their feet, Garrett ripped off Rudolph’s helmet and swung wildly, hitting the second-year player on top of the head.

Garrett was thrown to the ground by Steelers guard David DeCastro, and Pouncey threw punches and kicked Garrett in the head as players from both sidelines poured onto the field in a scene that goes to the top of the list of skirmishes in the bitter Pittsburgh-Cleveland rivalry.

“I don’t know how he got to the point that it’s OK to use a helmet as a weapon,” Steelers defensive tackle Cameron Heyward said. “I know we play a sport that’s violent, but it should never have gotten handled like that. That dumb stuff shouldn’t be allowed. For someone to use a helmet as a weapon is uncalled for.”

Garrett, Pouncey and Ogunjobi were ejected.

A self-described pacifist and poet, Garrett apologized to coach Freddie Kitchens and said he intended to talk to his teammates.

“The next time I see them, I’ll address them,” he said. “I am hurting my whole team with what I did, and it could come back to bite us. I don’t know what kind of repercussion I face, but I have to be better.”

The Browns will visit the Steelers on Dec. 1.

Kitchens clearly was not happy with Garrett for losing his cool and overshadowing a huge win for the Browns, who have won two straight games to salvage a season that was starting to slip away.

“You have to be able to maintain your composure in times like that and under no circumstances do we want anything to do with anything like that,” Kitchens said. “I am embarrassed. Myles is embarrassed. It is not good. He understands what he did, he understands it is totally unacceptable, and we have to get through it.”

The Browns have been among the league’s most penalized teams, and their lack of discipline has been a poor reflection on Kitchens in his first year as coach.

Cleveland committed eight penalties for 121 yards against the Steelers, and Browns defensive backs delivered two helmet-to-helmet blows that gave concussions to Steelers wide receivers.

The second such shot was by Browns safety Damarious Randall, who lowered his head and delivered a nasty hit on Steelers rookie Diontae Johnson, who suffered a concussion and had blood coming from one ear.

Kitchens took issue with the idea his team is reckless, and said he was disappointed for his other players.

“We have five seconds to go in a game — the biggest game that this team has won,” he said. “Never beat Baltimore and Pittsburgh in the same year since 1999, and then we have to talk about this. There are 52 other guys on the team that that hurt, and it is going to hurt moving forward. We do not condone that. Myles understands what he did wrong.”