CHICAGO (CBS) — A BB-gun was turned over to authorities after one Palos Heights student brought it on a school bus and gave it to another student today, according to the Facebook page for Alan B. Shepard High School.

A male student at a south suburban high school is being questioned – following a two-and-a-half hour lockdown because of a report of a gun on campus or on a school bus, says the Cook County Sheriff’s office.

The principal of Alan B. Shepard High School says the school got word from a student just after noon that another student may have a gun – either on campus or on a school bus.

Principal Josh Barron says the school was on lockdown starting about 12:30 until about 3 p.m., when the lockdown was essentially lifted and students were allowed to leave a classroom at a time.

Barron told WBBM earlier, “We are searching the building… with the Cook County (Sheriff’s) Police Department. They just recently brought in dogs. And we’re going to go into each classroom one-by-one and make sure that there is no weapon in the building.”

No reports of injuries.

Barron says all after-school activities and competitions have been cancelled today..

Shepard High School in Palos Heights has about 1,800 students.