OMAHA, Neb. (WOWT) - An Omaha middle school started off the school day Wednesday with a person using pepper spray and several arrests.

Police were called to McMillan Middle School on Wednesday morning to respond to an incident.

In a letter to families, McMillan’s principal said the situation started when a former student used pepper spray in an entryway.

Staff members moved the person outside and called law enforcement. Officials say two families then started arguing, and one person flashed a knife.

An Omaha Police Officer then deployed the pepper spray.

Police say 10-15 people, adults and children, were involved. Several of them were taken into custody.

The school was placed in lockdown for 45 minutes while police investigated.