West Ham and Bayer Leverkusen players broke into a frantic melee as two coaches received red cards.
Hammers coach Billy McKinlay lost his cool at a member of Leverkusen's coaching staff and received a red card as the Europa League tie descended into chaos in the first half at the London Stadium.
3
And as the referee dealt with that situation, another fracas broke out on the pitch as Michail Antonio tried to wrestle the ball off Odilon Kossounou.
It ended in a mass melee with most players on both sides getting involved with Antonio and Leverkusen captain Jonathan Tah receiving yellow cards each.
It is not known what started the touchline quarrel, with McKinlay particularly animated as he gesticulated in one Leverkusen staff member's face.
The incident earned David Moyes' No. 2 a red card - while the Leverkusen coach was also sent to the stands.
READ MORE ON WEST HAM
Tensions are high in the London Stadium where the Hammers are chasing a two-goal deficit against Leverkusen.
Antonio opened the scoring after a delicious ball from Jarrod Bowen, who has returned to the side from injury to give Moyes a major boost.
And the West Ham goalscorer was at the centre of the on-pitch tussle after trying to take the ball off Kossounou.
The incident snowballed out of control with the referee already busy dealing with what was going on in the technical area.
Most read in Europa League
3
3
However, the melee subsided eventually allowing the referee to stand back and pull out the main perpetrators, who he decided were Antonio and Tah.
West Ham went on to lose 3-1 on aggregate to Leverkusen after a 1-1 draw at the London Stadium.
Jeremie Frimpong came off the bench to break Hammers hearts in the 89th minute to keep the German side unbeaten this season and send them through to the semi-finals.
Leverkusen were crowned Bundesliga champions for the first time in their history over the weekend.
Moyes, meanwhile, looks set to leave West Ham at the end of the season, talkSPORT understands.