The New York Red Bulls and Sporting Kansas City played out a 2-2 draw on Sunday night.
Sporting KC took the lead when Johnny Russell netted the opener.
However, the visitors battled back and looked like they would walk away with all three points courtesy of goals from Daniel Royer and Brian White.
But Gianluca Busio found an equaliser with just two minutes of normal time remaining to ensure the game ended in a draw.
That would have been hugely disappointing for the away side, who looked as if they had secured the three points.
One player from the travelling team let frustration get the better of him in stoppage time.
After his teammate failed to find him with a pass, Kaku responded by throwing his hand up in the air in disgust.
Standing on the touchline, he then blasted the ball at the crowd from just a few yards away.
Watch it below:
Why he felt the need to smash the ball at the home fans is anyone's guess.
According to Squawka, his moment of frustration connected with a fan and left them with a bloody face.
Quite rightly, Sporting KC players confronted him and a mass brawl quickly followed.
Kaku was eventually sent off and appeared to show remorse as he walked off the pitch.
The New York Red Bulls condemned his actions in a statement after the game.
"The New York Red Bulls organization does not condone the type of behavior displayed near the end of Sunday night's match in Kansas City," a statement on their club website read.
"The matter will continue to be discussed internally and we will have no further comment at this time."
Kaku has since apologised on Twitter for his actions.
"I want to take the time and apologize for my actions during tonight’s match," he wrote.
"As a competitor, I was frustrated with myself and took out my frustrations in a way that is not acceptable. I love this game and would never want to disrespect it."
"I apologize to the @SportingKC fans, my teammates, @MLS and to all @NewYorkRedBulls supporters," he continued.
After a fan called out his behaviour, Romero apologised once again.
"It was not my intention, my heart apologies 🙏🏽♥️😞@SportingKC," he wrote.