Several football players at a northwest Louisiana high school linked arms but remained standing as the national anthem played before their game Friday evening, after their principal came under fire for threatening to punish student athletes who protest during the national anthem.

As the announcer at Airline High School’s stadium, where Parkway High School’s football team played Friday, asked the crowd to rise for a prayer and the national anthem, some Parkway players silently linked arms in their white jerseys, forming a line down the sideline.

A female student delivered the prayer, thanking Jesus. An African American man in the front row of the stands wore a Colin Kaepernick jersey.

As the band played the anthem, Parkway’s coaches stood at the end of the line in black windbreakers, their hands over their hearts. When the anthem ended, the Parkway stands erupted in cheers of “U-S-A! U-S-A!”

Parkway Principal Waylon Bates had announced Thursday that student athletes must “stand in a respectful manner throughout the national anthem during any sporting event in which their team is participating.” Those who protested would face suspension from the game or the team, he wrote in a letter sent to students and parents.

The order drew a swift backlash from the American Civil Liberties Union of Louisiana, which issued a statement saying the policy ran afoul of a 1943 U.S. Supreme Court ruling that determined public schools could not force students to stand for patriotic rituals.

“As long as they’re peaceful, students cannot be forced to engage in expressions of opinions that they do not share. And you cannot make that conditional of taking part in a school activity,” said Marjorie Esman, executive director of the ACLU of Louisiana. “It’s counterproductive in addition to being illegal, to tell students they can’t express their dissent.”

NFL players across the country have been protesting police brutality and racial injustice by kneeling during the national anthem, a gesture that President Trump has fiercely criticized. Recently, some players have linked arms while remaining standing in what Green Bay Packers quarterback ­Aaron Rodgers called a display of “unity and love.”

Zandra Ashley, whose 18-year-old son played football at Parkway last year, said she believed the principal’s order crossed the line. Her son, Kameren Ashley, said that he and a teammate silently protested police brutality during the anthem at a game last year by turning their backs to the flag. He said the coaches responded with looks of confusion but did not punish them.

Coaches at the game would not comment.

“It would be different if we all sat down as a community to discuss why we felt the need to protest,” said Zandra Ashley, 34, who is black. “But it seems more like a dictatorship where those who are in high positions are telling us that our voice doesn’t matter. That we should just follow suit and keep our mouths shut.”

Before the game, Lakeshia Johnson — who has two children in elementary school and two nieces of high school age — said she didn’t believe students should “be punished for following the First Amendment.”

“I’ve heard a lot of [African American] kids saying they want to protest,” said Johnson, who is black and said she has two brothers in the military, “but they’re scared of consequences, because a lot are in active sports like football, band and pep squad.”

Bossier Parish Schools Superintendent Scott Smith, whose district includes Parkway, issued a statement Wednesday saying ­extracurricular activities are “a privilege, not a right,” and that individual principals in his district would determine responses to student-athletes who did not stand for the national anthem at sporting events.

Shortly before the game began, parent Jamie Miller said her son, who is a football player, had received the principal’s letter, but said “he doesn’t need it.” He had always planned to put his hand over his heart during the anthem, said Miller, who is white.

Earlier that day, football players standing outside Parkway’s field house said they had never planned to protest during the anthem.

“No matter what goes on, this is our team and we’re equal,” said sophomore Malik Moore, who is black.

The warnings issued by administrators in Bossier Parish schools came after a high school principal in neighboring Caddo Parish said Tuesday that he and his school’s players intended to link arms during the national anthem.

The two parishes, separated by the Red River, have very different demographic compositions and political leanings. Caddo Parish schools are predominantly black, and the parish is one of just 10 of Louisiana’s 64 parishes that Hillary Clinton won in the 2016 presidential election. Bossier Parish schools are predominantly white, and President Trump received 71 percent of the vote in the parish.

Mary Nash-Wood, a spokesman for Caddo Parish Public Schools, which includes the city of Shreveport, said district officials received guidance Monday from the Louisana High School Athletics Association and the Louisiana Association of School Boards that it would be left up to individual school districts to determine how they would respond to potential protests by student- athletes.

“For Caddo, it was, ‘We’re going to err on the side of each student’s individual rights,’ ” Nash-Wood said.

An attorney for the district cited the 1943 Supreme Court decision that found forcing students to recite the Pledge of Allegiance would violate the rights of students who were Jehovah’s Witnesses.

Bossier Parish schools spokesperson Sonja Bailes declined to comment when asked what the legal basis for the district’s position was.

Parkway football coach Neil May also declined to comment on the issue. April Rogers, an office manager at the high school, said Principal Bates was not commenting and referred questions to district headquarters.