RICHBORO, Pa. (CBS) – A threat made on social media prompted a brief lockdown at a Bucks County middle school Monday morning.

School officials say Richboro Middle School was placed on lockdown shortly after 11 a.m. after a student alerted the principal of a threat made on Snapchat.

The lockdown was lifted around 12:20 p.m. after police found it was safe to proceed with class.

The school says Northampton police will remain at the school for the remainder of the day as a precaution.

The threat remains under investigation.