An adult student who showed up with a hammer was taken into custody following the 8 a.m. lockdown, Acting Union County Prosecutor Lyndsay Ruotolo said.
The hammer and a knife were subsequently recovered and a second student was removed from the building before the lockdown was lifted, the Union County Prosecutor's Office said.
A second lockdown that lasted several hours was imposed around 11 a.m. by school security on reports of a firearm in the building, authorities said. A search of the building turned up no evidence of a firearm, a prosecutor's office spokesperson said.
"As rumor spread through the student body, a large group of students ran from the building prior to the arrival of law enforcement, resulting in an inadvertent injury to one student during the flight," the UCPO said.
"Stay safe" and "I'm scared to death" were some of the messages posted by students to social media during the lockdowns.
The incidents were unrelated and remain under investigation.
Click here for more from ABC7.
Click here to follow Daily Voice Englewood and receive free news updates.