Norwich — The John B. Stanton Elementary School on Norwich-New London Turnpike was briefly placed on lockdown Friday after a visitor to the main office displayed erratic behavior, according to School Superintendent Abby Dolliver.

Dolliver said the unidentified man was not threatening but was erratic enough that office staff called 911. The school was placed on lockdown as a precautionary measure. The man left before police arrived but was stopped by police a short time later, she said.

Dolliver said the school is a secure facility with locked doors and cameras. Office staff allows visitors to enter based on their interaction. Dolliver said she is still investigating why the man was allowed to enter.

Parents of Stanton students were notified of the 2:50 p.m. incident with a voice message from the school. The lockdown lasted less than 10 minutes.

Norwich police provided no further information.