BELLEVILLE, Ill. – Belleville West High School went on lockdown and dismissed early Monday after a student brought a gun to school but had it stolen during gym class.

The Belleville Police Department said they got a report at around 11:15 saying a student had his loaded gun stolen from his gym locker.

The school was put on lockdown when they were told of the loaded gun. Police then helped the school with a controlled dismissal where all the students were escorted out of the school by police.

"I knew it wasn't a drill as soon as I saw three, four cops walk up,” freshman Aly Roberts said. "I was assuming there was an active shooter."

The investigation is ongoing and several students are being interviewed. Police did not say if the gun was found.

Aly immediately texted her mom.

"I just fell out at work and started crying. Couple of other people I work with have kids who go there and we just kind of huddled together and started praying,” mom Ashley Winchester said.

We asked police if they found the gun, and they didn't respond.

While Ashley says she believes the school handled the situation appropriately, she still has questions about the investigation.

“It’s still nerve-wracking we don't know who it was, if it's been found, what's happening,” Ashley said.

Aly says she’s anxious to return to class.

“I’m super nervous. You never know what could happen. You don’t think about stuff like that until you go through it,” she said.

The school shared this on their Facebook,

‘The reason there may be a delay in the dismissal of your student is because the Belleville Police Department and other local law enforcement agencies are at school assisting staff for a systematic dismissal of students. Students are being taken to a safe location for dismissal. We understand this is a stressful time if you have to wait for the dismissal of your students. Please understand we are acting with an abundance of caution for the safety of our students and staff. This is an ongoing investigation as the Belleville Police Department.’

This story will be updated as we receive more information.