Some parents are outraged that a Florida high school conducted an unannounced "code red drill," sending students and teachers into a panic.

voice announcing a “Code Red” over loudspeakers at Lake Brantley High School sent some students and teachers into a panic Thursday morning, frightened that an active shooter was targeting people on campus.

The alert was part of an unannounced drill, which infuriated some parents who worried their children were traumatized by the experience.

Megan Storm, 16, said she was in her AP Music Theory class when she heard someone say “Code Red” over the loudspeaker. She said the announcement didn’t mention the threat wasn’t real.

Megan said she and her classmates hid in the back of a locker room for 20 minutes. Other students were texting their parents to let them know they were OK, but Megan didn’t have her phone and wasn’t able to speak with her parents until the drill was over.

“I wasn’t really sure what was going to happen,” Megan said. “But based on all the stuff you hear … you think there’s [ a shooter] who is going to get you.”

Michael Lawrence, a spokesman for the school district, said the panic was not primarily caused by the drill, but by a student who later shared a screenshot of an alert that some teachers had received during the “Code Red.”

“Active Shooter reported at Brantley / Building 1/ Building 2 and other buildings by B Shafer at 10:21:45. Initiate a Code Red Lockdown,” said the automated text-message alert received by teachers. The alert gave no indication the threat was a drill.

Lawrence said that message was shared among students on Snapchat during lunch, causing a second panic. In a recorded message to parents Thursday evening, Lake Brantley principal Dr. Trent Daniel also attributed the panic to a social media post.

“Administrators believe that students are responsible for the posting,” she said, adding that the post is being investigated “as a disciplinary matter and all responsible parties will be disciplined.” She said the drill was “standard practice” and “went well.”

Lawrence said the district’s schools often conduct drills — some of them unannounced — and immediately alert parents with automated messages. “I think today the message did go out, but I think it went out a little bit later than we normally do,” he said.

Lake Brantley High School administrators posted a message on the district’s Facebook page at 11:12 a.m., nearly an hour after the drill began: “This morning at approximately 10:21am, LBHS conducted a Code Red Drill on our campus, performance by Seminole County [Sheriff’s Office]. This was only a drill to continue to practice for the security and safety of our students. Thank you!”

Dozens of angry parents responded to the message, wanting to know why there was no notice of the drill.

“Getting a random mid-day text from my son that says ‘I love you - there is a shooter on campus’ is not the way I want to be notified of a drill,” said one person who posted a comment.

“Nothing is more terrifying than getting a text from your daughter who is hiding in her classroom having a complete anxiety attack because they are under a code red with an active shooter on campus,” read another comment. “I understand practicing safety, but this was completely the wrong way to go about it and is completely unacceptable!”

Lawrence said the only way to prepare students for real-world threats is to conduct drills without prior warning.

“The reason we do unannounced drills are so people will take it seriously,” he said. “The only way to get their attention and ensure they’re doing what they’re supposed to do is to do the unannounced drill.”

But Megan Storm’s father, David Storm, said he worried that not announcing the drill would cause students to not take a “Code Red” seriously in the event of a real threat in the future.

Thursday was Megan Storm’s birthday. She said she planned to spend the rest of the day eating a homemade gluten-free cake with her parents — and relaxing.

Renee Storm, Megan’s mom, said she understands the school district is faced with the difficult task of protecting students from shooting threats. But, she said, the school also needs to take the students’ mental health into account when planning active-shooter drills.

“It’s more than just protecting children from bullet holes,” Storm said. “It’s protecting them from the anxiety and trauma they’re now experiencing.”