CHAPEL HILL -

UNC has issued the an "all clear" message to the campus community after a Sunday afternoon emergency notification.

The all clear signal means the threat to the campus is over.

According to WTVD, the person who caused the lock down is in custody.

The person, a male, had a knife, but no one was hurt, WTVD reports.

At 4:29 p.m., an alert was posted on the university's website, saying police reported an armed and dangerous person on or near campus.

Emergency sirens were activated.

The sirens are activated when there is a significant emergency or immediate health or safety threat to the campus community.

We'll update this story as it develops.