Several German soccer players could face discipline after they showed support for the slain George Floyd with on-field tributes over the weekend in the Bundesliga.

Floyd, a 46-year-old black man, was killed while handcuffed and pinned to the ground by a white police officer Monday in Minneapolis. His death has sparked protests throughout the United States and in Europe.

Bundesliga rules prohibit players from political demonstrations and messages on equipment while they are on the field. The German Football Association, the governing body for soccer in Germany, said it will investigate the tributes.

Borussia Dortmund winger Jadon Sancho scored three goals in a 6-1 win against Paderborn Sunday in Paderborn, Germany. He scored his first goal in the 57th minute before he walked down the sideline and pulled off his jersey. Sancho revealed a message on his undershirt, which read: “Justice for George Floyd.”

“Delighted to get my first career hat trick, a bittersweet moment personally as there are more important things going on in the world today that we must address and help make a change,” Sancho wrote on Instagram.

“We shouldn’t fear speaking out for what’s right. We have to come together as one and fight for justice. We are stronger together!”

Sancho’s teammate, Achraf Hakimi, also had a message in support of Floyd written on his undershirt. He pulled up his jersey after a goal in the 85th minute.

Sancho received a yellow card for taking his shirt off while Hakimi was not disciplined. The German Football Association said the yellow card had “nothing to do with [Sancho’s] declaration of solidarity.”

Borussia Monchengladbach beat Union Berlin 4-1 Sunday in Monchengladbach. Monchengladbach’s Marcus Thuram also referenced Floyd after he scored in the 41st minute of the victory.

The French striker headed a shot past Berlin keeper Rafal Gikiewicz before he pumped his fist in celebration. He then took a knee on the edge of the box for several seconds before he got back in position.

“Together is how we move forward,” Thuram wrote on Instagram. “Together is how we make a change. Justice for George Floyd.”

Monchengladbach posted a photo of Thuram’s tribute on social media with the words “no explanation needed” as the caption.

American midfielder Weston McKennie wore an armband that read “Justice for George Floyd” during Schalke 04’s 1-0 loss to Werder Bremen Saturday in Gelsenkirchen.

Hoffenheim edged Mainz 1-0 Saturday in Mainz. Bayern Munich also had a dominant performance Saturday with a 6-0 win against Fortuna Dusseldorf. Eintracht Frankfurt beat VfL Wolfsburg 2-1 Saturday in Wolfsburg. Hertha Berlin beat FC Augsburg 2-0 Saturday in Berlin.

“These reviews are also aimed at determining whether the game and the field are the right place for these actions,” the German Football Association said.

“Internationally, the immediate phase of the game should remain free of political statements and messages of any kind. The focus should be on the sporty and fair competition stand, before and after the whistle there are of course possibilities for appropriate actions.

“It remains to be seen whether there will be sanctions in these cases. ”

German Football Association president Rainer Koch said he was “proud” of the players.

“I can absolutely understand the actions last weekend,” Koch said. “What happened in the U.S. can’t leave anyone indifferent.”

The Bundesliga continues with the conclusion of matchday 29 on Monday. FC Koln faces RB Leipzig at 2:30 p.m. EDT in Cologne. The game will air on FS1.