Campuses in the Crandall Independent School District were placed under building confinement for about an hour on Tuesday afternoon.
According to the district, the precautionary measure was recommended by Chief Dean Winters with the Crandall Police Department because of an incident in nearby Combine.
The Kaufman County Sheriff's Department told NBC 5 someone in Combine was firing a gun on their own land which prompted a call to the police. That call also triggered the confinement.
The confinement means visitors were not allowed on campus.
Crandall and Combine are both in Kaufman County, where a massive investigation is underway for the person or persons who killed Kaufman County District Attorney Mike McLelland, his wife Cynthia and Assistant District Attorney Mark Hasse.