West Ham United players clashed with a group of AZ Alkmaar fans who attacked an area where friends and family were watching the second leg of their Europa League semi-final tie.
Michel Antonio and Syed bin Rahma were among those who tried to intervene in the clash after the Premier League side reached the final.
BBC commentator Alistair Bruce-Ball, who was in the stadium, said he saw AZ fans punching.
“These are horrific scenarios,” he said.
The family of the Alkmaar player clashed with West Ham fans during the first leg at the London Stadium last week.
Hammers manager David Moyes said his players were outraged by what happened at the AFAS Stadium.
“We need to wait for the dust to settle to see what it is, but the biggest problem is the area where the players’ families are,” he said.
“That’s the problem, a lot of players are angry because they can’t see if they’re okay.
“We’re going to have to wait and ask the officials what exactly happened. I can only tell you the players were involved because that was the home zone.”
West Ham beat their Dutch opponents 1-0, 3-1 on aggregate on the night to reach a major European final for the first time since 1976.
Moyes said his own family and friends were in the area that was attacked, adding: “I didn’t want to spoil our night in any way. It’s not West Ham supporters looking for trouble.
“Am I worried? Yes, my family is there, I have friends in that part. You hope they’ll try to distance themselves from it.
“Security wanted to take me in, but I had to make sure my players weren’t involved.”
AZ boss Pascal Jensen said: “What happened last week was very unfortunate and then you have the same feeling as what happened tonight.
“I’m a little ashamed of what happened in our stadium, but you have to control your emotions.”
Former Hammers midfielder Joe Cole, who is part of the BT Sport squad, said the game was “ridiculous”.
“Grown men attacked West Ham fans,” he said. “Players try to get involved and break it.
“AZ Alkmaar fans showing up in balaclavas and pumping their fists is ridiculous. There are families.”
“I can see someone punching”
Commenting for BBC Radio 5 Live at the AFAS Stadium, Bruce-Ball described the scenes as “unpleasant”.
“Some fans in dark jackets and hoods ran to the lower tier to express their displeasure, we had trouble on the right hand side,” he told the audience.
“The problem here is I think family and friends at West Ham were in that area. Those were very, very unpleasant scenes.
“The West Ham players were stopped. I could see the boxing in the distance.”
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