New York Red Bulls midfielder Kaku was shown a red card for kicking into the stands a ball that struck a fan late in his team's 2-2 draw at Sporting Kansas City on Sunday.
Kaku, whose full name is Alejandro Romero Gamarra, fired a ball from close range into the first few rows of seats in the 93rd minute. The ball struck a fan, who was left dazed with a bloody face and received medical attention, a source told ESPN.
Kaku tweeted an apology after the game, writing: "I want to take the time and apologize for my actions during tonight's match. 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."
Red Bulls midfielder Daniel Royer said Kaku did not intend to strike the fan with the ball but "definitely meant to hit the board" below the first row of seats. Coach Chris Armas said he thought Kaku was upset at a misplaced pass moments earlier.
Kaku was dismissed with a straight red card, and after a scuffle near the sideline, Red Bulls goalkeeper Luis Robles and Sporting KC forward Krisztian Nemeth were both issued yellow cards. Sporting KC tied the game minutes earlier with 16-year-old Gianluca Busio's third goal in as many MLS games.
In a gesture of goodwill, many Red Bulls players approached the stands to check on the fan immediately after the game.
"I know that [Kaku's] remorseful about it. I know that he didn't mean to do it," Robles told the Kansas City Star. "We all checked in with the guy. I guess that's the price you pay when you sit in the front row, right?"
Busio salvages draw with late equalizer for SKC
Winger Gianluca Busio, 16, scored in his third consecutive game for Sporting KC to earn a share of the points against the New York Red Bulls.
Sporting KC defender Andreu Fontas gave the injured fan his jersey and said he had a clear view of the play.
"It was a very, very, very hard ball that he gets in his face," Fontas said. "I felt very bad for him because he was here to enjoy and to see a good show, a good match, and he doesn't deserve this. I went after [the game] to give him my jersey because I felt very bad for him and [wanted to make him] feel a little bit better. I said, 'I hope you're OK. Thank you for the support.'
"It's bad luck, and for sure, the other player of the other team didn't want to hit him in his face, but it was one of the hardest things I've seen in a stadium."
Kaku will most likely face a multigame suspension. In 2017, Colorado Rapids goalkeeper Tim Howard was suspended for three games following an altercation with a fan. A source told ESPN at the time that Howard grabbed a Sporting KC fan by the arm as players were leaving the field.
At times this season, Kaku has been at odds with the Red Bulls after being linked with a move to Club America, one of the largest clubs in Mexico.
His agent told ESPN Mexico that the Red Bulls wanted $12 million to sell Kaku -- double what the Red Bulls paid Argentinian club Huracan a year earlier to acquire him -- and America balked at the price tag. Kaku told ESPN Mexico at the time that the Red Bulls' asking price was "not reasonable."
Then in March, the Red Bulls unexpectedly left Kaku out of the matchday squad for a game against San Jose, with Armas saying only, "We had a minor internal issue, and we dealt with that quickly."
The Red Bulls released a statement late on Sunday night, saying that they "do not condone the type of behavior displayed near the end of Sunday night's match" and that "the matter will continue to be discussed internally."