Multiple NFL teams cancelled scheduled practice sessions on Thursday in the wake of protests against the police shooting of Jacob Blake in Wisconsin.
After a day of tumult in US sport on Wednesday, when a boycott by the Milwaukee Bucks forced the NBA to halt its playoff schedule and prompted other sports to follow suit, NFL teams reacted on Thursday by halting training camps.
The Green Bay Packers, Indianapolis Colts and the New York Jets all scrapped practice sessions with the start of the new season only a fortnight away.
"The Colts will not practice today," Indianapolis said in a statement. "Instead the team will use the day to discuss and work toward making a lasting social impact and inspiring change in our communities."
The Washington Football Team also postponed a scheduled practice game at the team's FedEx Field.
"The players, coaches and football staff will meet as a football family and we will continue our open dialogue on the issues of racism and social injustice in our country," head coach Ron Rivera said in a statement late on Wednesday.
"We are all in this together."
US sport reacted with outrage to the shooting of Blake in the Wisconsin town of Kenosha on Sunday.
The 29-year-old was shot seven times in the back by a police officer as he attempted to get into a car containing his three children.
Major League Baseball, Major League Soccer and the ATP/WTA Western & Southern Open tennis tournament all halted play following the Bucks boycott.