NEW YORK (CBSNewYork/AP) — Choir students from Waynesville, North Carolina, visited the 9/11 Memorial last Friday and tried to sing the Star-Spangled Banner.

In the middle of their performance, however, they were approached by two security guards who told them to stop, because the singing could be considered a public demonstration.

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“They actually asked when are we going to sing? Are we going to sing? I said, ‘Well, we hadn’t planned on it, let me go check with the security guard,'” choir teacher Martha Brown told CBS2’s Raegan Medgie.

A spokesperson for the memorial said the situation was mishandled and that they are working with the security staff to make sure it doesn’t happen again. The spokesperson has apologized to the group.

Brown said one security guard at the memorial plaza had given the students permission to sing, but another guard told them to stop.

“Lots of people gathered around to listen and we thought the security guard who stopped us, we thought he was coming … so he could hear better,” Brown said.

Brown said the security guard told them they needed a license to sing.

“I can’t remember his exact words, but he did use the terminology, ‘This could be defined as a public demonstration, you’re going to have to stop unless you have a license, and I don’t see you on a list for today,'” Brown explained.

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The choir left the park after they were told to stop singing.

“That space is being protected by rules that if we’re allowed to just sing, other groups might be allowed to do things that are not respectful,” Brown said.

Student Laurel Causby said she wasn’t mad about the situation.

“I feel I was supporting the people who died that day and supporting my country,” she said.

Groups wishing to perform at the Sept. 11 memorial are supposed to apply for a $35 permit. The North Carolina group did not.

The choir has been invited back for another visit.

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