Bengals right tackle La’el Collins and Rams defensive end Leonard Floyd were the main combatants in each fracas. During the third and most explosive scrum, Los Angeles defensive tackle Aaron Donald swung a Bengals helmet several times into the mass, landing at least one blow on top of an opponent’s helmet.

After the coaching staffs separated the players, Bengals head coach Zac Taylor and Rams head coach Sean McVay decided to stop the practice. The teams had about 30 minutes left in their planned schedule.

“It just got a little scuffly, and so we just called it,” Taylor said. “We were in the last period, and we got two really good days of work in. So was it worth getting the extra couple of plays? Nah. So we called it off. We got two days of work in and we’ll go play on Saturday.”

“Just like Zac would say, I expect our guys to defend their teammates and vice versa,” McVay added. “There are certain things (where) you just don’t know what occurred. My understanding is that nobody got injured and that’s the most important thing. We’ll move on.”

Fights have been commonplace in joint practices across the league this summer, but the Rams and Bengals were confident their sessions would be void of such drama given the friendship and working history between the two head coaches. For the duration of Wednesday’s session, that was the case, as there wasn’t so much as light shoving between snaps in what both sides called a “productive” day. The teams also featured strict “no-tackle” rules, in which physical thud-tackling was allowed but not tackling to the ground.

It’s unclear exactly where things started going wrong Thursday, although in the first competitive drills of the day — where the Bengals offensive linemen were going one-on-one and two-on-two against the Rams defensive line — Floyd beat Collins twice.

If there were any concerns about emotions being raw from the Rams’ Super Bowl victory six months ago, this wasn’t that. Collins was the prize piece of this year’s Bengals free-agent class, agreeing to a three-year, $21 million deal in March after seven seasons in Dallas, so he wasn’t on the roster in February.

But Collins is just getting up to speed after starting camp on the non-football injury list with a back issue, and save for a walk-through Friday, the joint practices Wednesday and Thursday marked his first live-action in 11-on-11 work since the Cowboys’ playoff loss to the 49ers in January.

He and Floyd are very familiar with each other from matchups between both of their respective former teams (Floyd was initially drafted No. 9 by Chicago in 2016). Collins is no stranger to fights. While with Dallas last year, he was ejected in Week 14 for fighting after a late hit on quarterback Dak Prescott. Collins threw punches at Washington’s Will Bradley-King in the incident.

It was well into the initial 11-on-11 period Thursday when Floyd and Collins first fought, at the end of play in which Ja’Marr Chase hauled in a 40-yard bomb from quarterback Joe Burrow. Players from both teams rushed in and then separated just as quickly as the twos took the field. Rams director of football affairs Jacques McClendon dove into the scrum and physically pulled away defensive tackle A’Shawn Robinson, who was visibly agitated.

When the ones returned, so did the animosity as Floyd and Collins went at it again. This time, Collins ended up holding a Rams helmet, which he tossed away from the action. Again, coaches and assistants separated players.

The teams went into special teams work after that, but it hardly served as a pressure valve. Two plays after resuming 11-on-11 work, Collins and Floyd went at it again. This time, both players threw multiple punches as numerous members of each team joined the fray, including Donald, who swung a Bengals helmet at Cincinnati players several times. The practices were closed to the public, but friends and family of the teams and Bengals-affiliated corporate partners were in attendance, and multiple videos quickly surfaced that show Donald also falling backward onto the ground, with Bengals helmets in each hand.

Once the coaches got things settled down, the Bengals retreated to the area behind the end zone while the Rams went to their sideline. The only player who remained on the field was Rams cornerback Jalen Ramsey, who took the opportunity to work on hand placement technique with Bengals wide receivers coach Troy Walters.

Taylor and McVay decided to end the practice a few minutes later, with the Bengals leaving the field first and the Rams waiting until they were gone to exit.

Donald was originally scheduled for a press conference after Thursday’s practice but ultimately declined. Through a team spokesperson, Donald declined an additional request for comment about the situation.

“Especially when you start throwing punches with gear on, I’ve been enough of a meathead in my past where I’ve done some stupid stuff, too,” said McVay, who furiously dove into the final scrum in an effort to pull players apart. He declined to specify how the fight started or escalated.

“I know how volatile and how fragile it is where you hit it the wrong way, you break your hand and it could affect a guy’s chance to be OK — or God forbid, someone gets hit in the head with a helmet off … I don’t know what emotions I was feeling right there, I was just glad when everything got broken up and my understanding was that everybody is OK.”

The Rams declined to comment further on the situation, deferring instead to McVay’s comments in his press conference. The NFL defers to teams on matters that occur during practice when it considers disciplinary action, so it’s unlikely that Donald will face league-sanctioned discipline.