The NFL has suspended Detroit Lions safety Brian Branch for one game for unsportsmanlike conduct, the league announced on Monday afternoon.

Jon Runyan, the NFL vice president of football operations, issued the suspension for a violation of Rule 12, Section 3, Article 1, which prohibits unsportsmanlike conduct and applies to “any act which is contrary to the generally understood principles of sportsmanship.”

The incident that resulted in the suspension seemed to stem from Branch ignoring the handshake attempt of Chiefs quarterback Patrick Mahomes after Kansas City’s 30-17 victory on Sunday night.

Kansas City wide receiver JuJu Smith-Schuster appeared to say something to Branch about his action, and the former Alabama defensive back responded by hitting Smith-Schuster in the helmet, sending the wide receiver to the turf and sparking an altercation that brought players running.

In a letter to Branch, Runyan wrote: “Your aggressive, non-football act was entirely unwarranted, posed a serious risk of injury and clearly violated the standards of conduct and sportsmanship expected of NFL players. Your conduct reflected poorly on the NFL and has no place in our game.”

Branch has the option of appealing the punishment. Under the Collective Bargaining Agreement between the NFL and its players association, a hearing officer jointly appointed and compensated by the NFL and NFLPA to decide appeals of on-field player discipline would decide on Branch’s case.

If Branch is out, he will miss the Lions’ game against the Tampa Bay Buccaneers, which is a Week 7 Monday night contest on Oct. 20.

Because Branch is suspended without pay, a one-game absence would cost him about $76,625 based on an 18-week season.

After the game, Branch said Smith-Schuster had illegally blocked him in the back on Sunday night without incurring a penalty.

“I did a little, childish thing,” Branch said, “but I’m tired of people doing stuff in between the play, and refs don’t catch it. Like, they trying to bully me out there, and I should have never did it, but it was childish. …

“I got blocked in the back illegally, and it was in front of the ref. The ref didn’t do anything. And just stuff like that. I could have got hurt off of that, but I still shouldn’t have done that.”