Everton fans were caught up in a mass on-pitch brawl in the second half as one supporter carrying a child appeared to attack a Lyon player.
Ashley Williams clattered into goalkeeper Anthony Lopes with his foreaem which sparked the fracas - with players from both sides running in to get involved.
And footage showed one fan appearing to lash out at an opposition player.
The man holding the small child was then caught lashing out, aiming two slaps at keeper Lopes.
Remarkably, Williams was only booked for his part in the melee and went on to score the equaliser for the Toffees.
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Former Chelsea player Bertrand Traore was also at the heart of the incident as he ran in to defend his teammate.
Former Everton man Martin Keown accused Williams of stirring things up and said: “Williams has incited trouble with the fans and the stewards got involved.
“The referee should be sending people off. There is a professional line which you don’t cross and they have.”
Traore and Williams were pulled over by the referee who was seemingly going to send the pair off, but issued only yellow cards.
One person on Twitter said: "Bet the child's mum won't be happy."
Another added: "That Everton fan throwing punches while holding a child is awful."
There were also calls for Everton to issue a lifetime ban to the fan, with one tweeter posting: "@Everton I sincerely hope that idiot with his child in his arms hitting a Lyon player gets banned for life. Poor kid."
Williams said after the game: "It's football, it is what it is, it's just what happens, it's football it's high emotions, we want to win the game."
Lyon keeper Lopes said: “I don’t know if it’s part of the English atmosphere to hit an away player, but it was like this.”
After Williams had levelled for Everton, it was Traore who put the Ligue 1 side back in front with a flick at the front post to pile the pressure on Toffees boss Ronald Koeman.
Nabil Fekir gave Lyon an early lead from the penalty spot after Mason Holgate was punished for a rash challenge in the area.
The game finished 2-1, which makes it four games without a win for the blue side of Merseyside.
Everton host Arsenal in the Premier League on Sunday, but Koeman's future is very much in doubt ahead of the fixture.