Harford Technical High School near Bel Air was put on lockdown for about 30 minutes Monday morning after an employee came into the building without reporting to the office, a school spokesperson said.

The person, identified by the school's principal as a male, walked in with a student around the start of classes, Harford County Public Schools Manager of Communications Teri Kranefeld said.

"The student was buzzed in but the person that followed did not report to the office," Kranefeld said. "The lockdown was immediately executed to allow law enforcement to conduct an investigation. The investigation revealed that the person who walked in with the student was an employee."

"The lockdown has since been lifted and students are safely carrying on with their day," she said Monday afternoon. "The students and staff should be commended for their vigilance. Although this was a false alarm, the critical incident plans and procedures in place were effective."

Harford County Sheriff's Office Spokesman Edward Hopkins said the school was not evacuated and social media reports that claimed a man had a gun were unfounded.

According to a recorded phone message sent to parents Monday morning from Charles Hagan, the school's principal, the unidentified person walked in the building behind a student who was late and did not report to the office as required. Hagan said a front office secretary saw the man and alerted Hagan, who called for a lockdown and for assistance from the Sheriff's Office, according to the message.

Hagan's message said the principal and others went through a security video and determined the man was a "HCPS non-Harford Tech employee who had not signed in or reported to the office as required."

Once the person was identified, the lockdown was lifted at 9:50 a.m., according to the message, which concluded with a reminder that all visitors are expected to report to and sign in at the office.