The Sudan ISD put its students and staff on a Level 1 lockdown for a time on Tuesday.
The classes continued as normal, but no one was allowed to come in or out for a time. The lockdown was publicly announced at 11:15 a.m. and was lifted by 11:36 a.m.
Sudan Police said a particular person had previously made threats against teachers and a football player. That person was spotted near the school Tuesday.
He was arrested but officials have not yet released his name.