Bethel Middle School was placed into a modified lockdown after bullet shell casings were found in the school Friday.
According to the school superintendent, the .22 caliber shell casings were on the floor just outside of the school cafeteria.
Police responded to the school at 600 Whittlesey Drive just before 10 a.m. Authorities originally said they spoke to a student believed responsible for the shell casings, but school administrators said there has been no student identified as being responsible and the investigation continues.
The modified lockdown means students can still move about freely in the school. It was lifted at 11:50 a.m., according to school officials.
Police conducted a second search of the building after the school day to look for any additional shell casings.