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A group of North Carolina middle school students who were ordered to stop singing the national anthem at the 9/11 memorial have received an official apology after awkward video of the incident went viral.

The Waynesville Middle School choir was visiting New York City for a three-day trip on when they stopped at the 9/11 memorial on April 20 and decided to sing “The Star-Spangled Banner” out of respect for the dead.

They never got to finish.

Before the song was over, two National September 11 Memorial & Museum guards walked over and told the students they had to stop singing.

“We thought they were there to listen, but then it all ended,” one student told WPIX in a interview on Monday.

“We just wanted to show respect to the people who lost their lives,” another student added.

The video, posted to Facebook, has been shared over 1,000 times with many people commenting that the students should not have been interrupted.

According to the 9/11 memorial’s website, groups wanting to perform must first obtain a permit. The Waynesville students didn’t have one, but did get verbal permission from a security guard that day, music teacher Martha Weathers Brown said.

Brown said the group gathered quietly and sang softly in what she describes as a “paying of respects through music.”

“It was a very moving moment, and it was unfortunate that it got cut off,” Brown said. “It was confusing to the students because they were singing from their hearts.”

A spokesperson for the memorial told WPIX in a statement that the guard “did not respond appropriately.”

“We reached out to the school to express our regret for how this was handled and asked the principal to share that with the students,” said Kaylee Skaar, a spokeswoman for the Sept. 11 memorial.

Brown added that she understands why they were told to stop and used it as a teaching moment about respecting authority, showing students that these rules are in place to protect a sacred space from people who might want to be disrespectful.

Despite the incident, the students had a great time, a school spokesperson said. While in New York, the students sang at the Cathedral of Saint John the Divine, attended “The Lion King” on Broadway.

All 51 students have been invited back for a future visit.