Rockville High School was placed into lockdown for a short time Friday morning.
According to police, a teenager walked into the main office and signed in using someone else's identity at 7:47 a.m., leading to concern.
Police arrived at the school at 70 Loveland Hill Road to search for the individual, but determined the teen left the building by 8:30 a.m., according to authorities.
The school released a statement saying an unathorized person entered the high school at 9 a.m., the students stayed in locked classrooms as police officers searched, and the search was over by 9:55 a.m.
Police do not know the name of the teenager and continue to look for him.
School officials said the students are following a normal school schedule after the lockdown was lifted.
