DeLand High School student caused a scare Tuesday when some students thought his cellphone case was a gun, school officials said.

The 15-year-old boy's cellphone case was shaped like a gun, and a student thought it was a real weapon in the teen's back pocket, so the student reported it to a teacher, officials said.

The school was placed on a 30-minute lockdown.

The 15-year-old, whose name has not been released, faces charges of disruption of an educational institute, a misdemeanor, officials said.

“We know that kids will be kids, but in today’s world, we must be vigilant,” DeLand police Chief Jason Umberger said in a news release. “I want to express to all of our young people out there that they should always feel comfortable coming forward with information. Even if you’re not sure, we want to know. We don’t know what we don’t know, so whether a potential threat is made through Snapchat, Instagram, Facebook, Twitter or something else. Take a screenshot and send it over. You never know, you could be saving the lives of your friends."

The school district has reported at least 18 threats – all not credible – since the Parkland high school shooting, officials said.

School officials urged parents to be vigilant.

"You have to have a discussion with your children regarding 'see something, say something' to a trusted adult. You have to monitor your children's cellphone and social media, and third, you need to check their backpack," said Volusia County Superintendent Tom Russell.