Two students were removed from the building after responding officers arrived to assist in a search and discovered them with a knife, the school district said on its website.
Another student was thought to be in possession of what appeared to be a firearm, prompting a lockdown around 10:30 a.m., police said.
Two students' searches yielded a plastic toy gun with a blaze orange tip and a Nerf-style gun, according to police.
Both students were in police custody, along with a third student who was identified during the investigation, police said.
The lockdown was lifted at 11:05 a.m.
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