Super League and the RFL are to launch an investigation into the ugly scenes that marred the end of Saturday's clash between Catalans Dragons and Warrington in Perpignan.
Catalans duo Sam Tomkins and Michael McIlorum saw red after the match for their role in an on-field fracas, while tempers also flared in the stands, with fans trying to climb over barriers to get to each other.
Warrington's Jake Mamo also received a second yellow card in the incident.
"We were appalled to see the pictures from Perpignan, and an investigation will be launched," read a joint statement from Super League and the RFL.
"The scenes are alien to Super League and have no place in our game. We will be taking firm action to make it clear this behaviour is totally unacceptable."
A Warrington statement explained that the club is "working in conjunction with Catalans Dragons and Super League to gather further information", while Bernard Guasch – the hosts' chairman – said: "We are now waiting for the CCTV footage before making any decision."
Warrington's release added: "We sincerely believe that this behaviour does not reflect the vast majority of our loyal and supportive fan base following the team in France this weekend."
Man of the match Tomkins had created three tries and kicked seven goals as Catalans claimed a 30-10 victory.
"We've always had good challenges against Catalans every time we play them," said Warrington coach Steve Price. "It was really disappointing how the game finished – you don't like to see that, do you?"
When asked whether he thought events on the pitch had influenced those off it, Price responded: "What do you reckon? I think you're answering the question yourself there."
"I'm clearly not happy with the whole of the game in terms of how it was managed," said McNamara. "After the game I will take that up with the relevant people.
"I think it is best to stay nice and calm and speak to the relevant people and deal with the issues that will be brought up from that game.
"I have no idea how (the scenes at the end of the game) have come about, but it's disgraceful scenes that we don't want to see in our sport and I'm sure, again, the relevant people will look into that and find out.
"I just sincerely hope that no one is hurt from that because it didn't look good."
McNamara did, however, hit out at a suggestion from Price that his side had deliberately slowed the game down.
"I'm sick and tired of every time a team comes here and complains about the tactics and how tough it is and how difficult it is," he said.
"I've said this numerous times, we have to do it 14, 15, 16 times a year. We face it every week when we travel away, yet teams want to whinge and carry on when they come here because it's our ground.
"The best team won today and the best team won by a long way in the end and that result was correct. Nothing to do with anything other than the better team won on the day, simple as that."
Price added that it was "way too early" to offer an update on the fitness of Blake Austin, who left the field with a suspected ankle injury.
The result meant St Helens took the League Leaders' Shield, with Warrington cut adrift.