About 75 students at Friendly High School in Prince George’s County who supported Breast Cancer Awareness Month by wearing pink shirts were given in-school suspensions Friday for violating the school’s uniform policy.

Students said they were sent to a classroom and told that they would receive an unexcused absence and zeros for their classes. But Max Pugh, a spokesman for the school system, said the students would be excused for missing class and would be able to make up any missed work.

Raynah Adams, principal of the Fort Washington school, told the students Tuesday that they could not hold their annual “Pink Out” because it would violate the uniform policy and there were security concerns, the students said.

But on Friday, a number of students showed up wearing pink shirts, pink sweaters and, in some cases, pink ribbons painted on their cheeks. Students estimated that 20 percent of the school population participated, but that figure could not be confirmed.

Syndi Wilson, a junior who was given an in-school suspension, said she was disappointed by the school’s reaction to the attempt to draw attention to a deadly disease that has taken many of her friends’ family members.

“I didn’t do this for myself,” Wilson said. “It’s for everybody — anybody who has lost a loved one to breast cancer.”

Pugh said that Adams ordered pink ribbons last week so that all students, regardless of their families’ income, could participate in the breast-cancer awareness effort. More than 40 percent of the school’s students come from families that fall within poverty guidelines. Adams planned to let the students wear the ribbons on their uniforms next Tuesday, Pugh said.

When several students arrived at school in clothes that violate the uniform policy, the school had a limited number of shirts to give out so some could attend class. The rest of the students were placed on in-school suspension, he said.

Jenae Foreman, a senior who also had an in-school suspension, said she was shocked to learn that Adams would not allow Pink Out, which was held at the school the two previous years.

Foreman said that her aunt and grandmother died of breast cancer and that she considered Pink Out a way to honor them.

She said she didn’t understand the severity of the punishment.

“I was shocked,” she said. “It wasn’t a riot. It was for a cause. . . . We were just paying reverence” to Breast Cancer Awareness Month.