Elon Musk used a Delaware County high school for a town hall. Some teachers are unhappy.

On the morning of Oct. 17, teachers closed the doors to their classrooms at Ridley High School, turned off lights, and instructed their students to silently huddle in the corner.

They were participating in an “active-intruder drill” in case an armed trespasser ever stepped foot onto the school’s property, said Brian Forney, a math teacher at the Delaware County school and the president of the Ridley Education Association, the union representing teachers in the district.

A few hours later, teachers and students were closer to an armed presence than they likely expected.

Security personnel were in tow at Ridley High on Thursday, thanks to a 600-person town hall hosted there by Elon Musk, owner of X and the richest man in the world.

The Ridley School District is defending the circumstances of the event, a voter-mobilization event powered by Musk’s pro-Donald Trump America PAC. Some teachers contend that the billionaire’s last-minute visit was a safety risk that intruded on their students’ school day.

“In general, I’m hearing a faculty that is still upset that this happened, that our school board allowed this to happen, upset that our school board is still claiming that this was a voter-registration drive, a voter-registration rally,” Forney said.

Security personnel — some of whom Forney says had weapons — started forming a perimeter at the school while classes were in session, in anticipation of Musk’s arrival.

“There were a lot of strangers in the lobby, some of whom [were] armed, some of them not,” Forney said. “Some of them could have been police officers. I don’t know, I didn’t really stick around to take a really close look … but I mean, clearly there were people with guns on their hips walking around.”

Ridley High School’s faculty and staff received an email from their principal that morning that campus was closed immediately after school, but did not specify why. When Forney left the school grounds at 2:45 p.m. that day, he noticed armored SWAT vehicles near the school.

“Our principal had asked all security personnel that were inside to go wait in the auditorium while kids dismissed,” Forney said. “But there was quite a few people outside on the front steps setting up as I left to go to my car.”

Neither the school board, which is entirely Republican, nor Ridley Township police made themselves available to answer questions on Monday.

The union’s qualm, Forney said, is not that Musk spoke at Ridley High — “the REA is not opposed to free speech, Second Amendment … all that stuff could be debated somewhere else.” The issue, he said, is safety.

Forney, 56, said other avenues could have been explored to avoid less overlap between students and preparations for Musk’s arrival: Host it on a weekend, or later at night, or send students home for a half-day.

“We don’t even let parents walk through our school unaccompanied,” said one teacher at the school who spoke anonymously because they were not authorized to talk to the press.

“His crew interrupted several classes, asking teachers to help with the setup while they were teaching. People with MAGA hats and sweatshirts lined the front hallway, and by 12:30 p.m. MAGA supporters had already started filling the parking lots and congregating on school property outside,” the teacher said.

“Doors were propped open, and a seemingly endless group of people moved around the school while it was in session — a thing that is never supposed to happen in a secure school environment.”

Musk’s visit wasn’t officially confirmed until the afternoon of Oct. 17, Forney said. But until then, the “rumor mill” was in overdrive with high schoolers buzzing about what could be happening.

“Everyone was riled up,” said 11th grader Brody Houston.

“At lunch they were all like, ‘Oh my God,’” said Cole Tran, another 11th grader, as the excitement built during the day.

In an email sent to parents, the school district maintained that everything was done by the book — and that the district “encourages healthy democratic practices during the election season.”

The Board of School Directors authorized a permit request for a “get out the vote/voter registration event featuring Elon Musk in the high school auditorium in line with district policy and procedures,” according to the email, which The Inquirer obtained.

In Greensboro, N.C. on Monday, Trump thanked Musk for his efforts to rally support for the GOP presidential candidate.

Attendees of Musk’s Pennsylvania town halls had to be registered to vote in Pennsylvania to participate, raising some legal red flags. They also had to sign a petition from Musk’s super PAC that, in part, pledges the signee’s allegiance to the First and Second Amendments.

Musk frequently strayed from the topic of voter mobilization in that Delco auditorium. The Trump loyalist delivered fear-stoking remarks about crime and immigration, spread misinformation about Pennsylvania’s election process and Vice President Kamala Harris, and painted an apocalyptic picture of the United States if Trump is not elected in November.

“Really the REA’s objection here is not politics, it’s school safety. Like, whether or not we agree with the politics is a whole other story,” Forney said. “If they held the rally on Saturday, we would not have the same level of upset that we have when they held the rally on a Thursday afternoon.”

Staff Writer Jesse Bunch contributed to this article.