UDPATED: North Farmington High School on Classroom Lockdown Thursday

UPDATE: A classroom lockdown at North Farmington High School was stepped down to a general lockdown, and access to the building will continue to be restricted throughout evening activities. 

"North Farmington’s lockdown was in response to an indirect threat referencing our school via social media. We became aware of these messages shortly after 7:00 AM this morning," Principal Joe Greene wrote in a list serv email Thursday afternoon. "We immediately secured the building, entered a classroom lockdown, and conducted a rigorous investigation in conjunction with the Farmington Hills Police Department. Our safety protocols worked well and our students and staff were safe as a result throughout the day."

Greene praised the response of students, staff and parents, along with the Farmington Hills Police Department. 

In a list serv message sent around 8 a.m., Greene wrote that the classroom lockdown "limits movement in the building, and still allows classroom activities to continue within the safety of their room. Although the threat did specifically target North Farmington, given recent events, we are taking these additional measures to ensure safety." 

Greene wrote the school continues to investigate the threats with Farmington Hills Police and will update parents as more information is available.

Schools around the country have been on high alert since a lone gunman entered a school building in Newtown, CT last Friday and killed 20 children and six adults, before turning the gun on himself. On Wednesday, Farmington Schools Supt. Susan Zurvalec asked all schools to lock their main entrances through the rest of the week. 

Also on Thursday morning, Genessee and Lapeer County schools canceled classes for the remainder of the week. According to a report on minbcnews.com, North Branch Area Schools Supt. Thomas English posted a letter on the school's website noting that while rumors about possible violence against students posed no credible threat, "these rumors have been a serious distraction for students, teachers, administrators, and parents."