Norwalk school officials are investigating a possible threatening message at Brien McMahon High School.

School officials posted to Facebook last night saying that, "A student notified a school administrator about seeing a possible threatening message at Brien McMahon. We immediately notified the Norwalk Police Department, which is investigating the report."

The school added extra security guards and police at building today. 

It is unclear what specifically the threat may have entailed.

Norwalk police say they are investigating.