Supporters of AZ Alkmaar clashed with riot police and West Ham United fans following their 1-0 defeat that saw the Dutch club eliminated from the Europa Conference League semi-final.
Pablo Fornals’ injury-time winner prompted a gang of black-shirted, hooded AZ ultras to attempt to storm into the area reserved for friends and family behind the dugout.
The incident is the latest in a series of escalating incidents of football violence in the Netherlands, which has worried both sports officials and politicians alike.
AZ fans stormed the main stand at the AFAS stadium in the northwest Dutch city shortly after the final whistle, before brawling with West Ham supporters celebrating the win, the ANP national news agency said.
"The fans sat behind the AZ goal and broke through a gate to the main stand, after which they stormed celebrating West Ham fans," the ANP said.
"From there, fists were flying," it added.
Several players from both teams were also pulled into the fracas including West Ham captain Declan Rice, midfielder Lucas Paqueta and Michail Antonio.
West Ham manager David Moyes, who’s 87-year-old father David Snr was at the match, said: “I can’t explain what happened and why it happened.
“I can only say the players were involved because it was the family section and most of their family and friends were in there. That was probably the reason for the reaction.
“Was I worried? Yeah, my family were there and I had friends in that section. You’re hoping they would try and get themselves away from it.
“I didn’t recognise it because I’d gone onto the pitch. Security wanted to take me inside, but I had to make sure my players weren’t involved.
“What we don’t want to do is in any way blight the night because it certainly wasn’t West Ham supporters looking for trouble. Hopefully they’ll look into it.”
Footage posted on Twitter showed a group of AZ supporters breaking down a gate before seeking confrontation with West Ham fans.
In yet another clip, several police officers in riot gear drive back AZ supporters before restoring order to the stadium.
Whistles condemning the fans' behaviour could also be heard from other AZ supporters in the stands.
West Ham goalkeeper Alphonse Areola added: “When families or friends are coming to the stadium we don’t want to see things like that. They want to enjoy the event and we want to enjoy it with them as well. We were worried about them.”
During last week’s first leg at the London Stadium, members of AZ players’ families were involved in a confrontation with West Ham fans.
AZ boss Pascal Jansen said: “What happened last week was very unfortunate and then you get the same feeling as what happened tonight.
“I feel a little bit ashamed it happened in our stadium but you have to control your emotions.”
The incident is the latest in an escalation in football violence in the Netherlands.
On Sunday a referee halted a top division match between FC Groningen and Ajax after a Groningen fan ran onto the field with a banner and smoke bombs were tossed on the pitch.
In another incident, Ajax midfielder Davy Klaassen received a head injury last month after a Feyenoord fan tossed a cigarette lighter at him from the stands.
West Ham have not reached a European final since the 1976 European Cup Winners' Cup, while the June 7 clash against Fiorentina in Prague will give the London side a chance to win their first major trophy since the FA Cup 43 years ago.
Reaching the European final is the bright spot of a poor season for West Ham, with Moyes' future looking uncertain at one point as they plunged into the relegation zone earlier this year, though they have since climbed to the brink of safety.
"We've all but stayed up and we're also in a final with a chance of winning a trophy, so there are a lot of positives that have come from it," Moyes said after the 1-0 win in the second leg.
"I've been in football and a manager for a long time and you don't get loads and loads of big opportunities.
"To actually get to a final is something which doesn't happen in many managers' lifetimes. I'm thrilled that I've had one or two, this is my first European one and it's something I'm really pleased with."
