FOXBOROUGH, Mass. (AP) — The NFL warned teams about fighting during games in response to inter- and intra-team altercations that have erupted in training camp, including the one that left New York Jets quarterback Geno Smith with a broken jaw.

In a memo obtained by The Associated Press, executive vice president Troy Vincent reminded all 32 teams on Friday that “fighting will not be tolerated.” Vincent asked coaches, general managers and club executives to remind players of the rules, and noted that the prohibition of fighting will be a point of emphasis for officials.

“These rules are in place for the protection and safety of our players and to keep them on the field,” Vincent wrote. “As professionals, no matter how emotional the game becomes, there is nothing that should resort to fighting.”

The memo cited Article 12 of the NFL rules, which prohibits “striking, kicking or kneeing opponents.” The penalty for a violation is 15 yards, with the official given the discretion whether to also eject the player from the game in the case of a flagrant violation.

The memo also cited the 2015 League Policy for Players, which says: “Don’t fight, and if a fight breaks out involving other players, stay away.’”

Training camp fights are a long tradition, with young players or others trying to make the roster attempting to impress coaches with their intensity but sometimes taking it too far.

Washington and Houston had several fights during a joint practice, one of them devolving into a bench-clearing brawl that caused no injuries but forced the coaches to separate the teams for the rest of the day. Cowboys receiver Dez Bryant and cornerback Tyler Patmon threw fists at each other in practice; Chiefs receiver Jeremy Maclin exchanged words and punches; the Titans had three scuffles in a night practice; and Carolina quarterback Cam Newton scuffled with cornerback Josh Norman.

Smith is out 6-10 weeks after he was punched by Jets linebacker Ikemefuna Enemkpali, who was immediately released and soon signed by the Buffalo Bills.