WESTFORD (CBS) – A 16-year-old was placed in custody after he allegedly entered Nashoba Valley Technical High School with an air soft rifle, forcing officials to place the school in lockdown on Wednesday.

Police responded to the school shortly before noon for reports of an “unwanted person” that entered the school through a rear door. Students leaving the school told WBZ-TV that an auto shop teacher subdued the suspect in the cafeteria before police arrived.

Officers said the weapon they recovered was similar to a BB gun.

WBZ-TV’s Diana Perez reports

The teen is scheduled to face charges including assault with a dangerous weapon and disturbing a school assembly. His name was not released because he is a juvenile.

No shots were fired. No one was injured.

WBZ NewsRadio 1030′s Laurie Kirby reports

The teen’s intentions were not known.

Once the lockdown was lifted, students were sent home early. Police said they intend to sweep the school a second time for potential threats.