A 17-year-old New Braunfels High School student was arrested Thursday after he made a reference to "shoot up" the campus, police said.
The New Braunfels Police Department found out about the threat, which was posted on Facebook, at 10:45 a.m.
Police said an adult in the San Antonio area saw the threat and was concerned about the safety of students and faculty at the school.
Police immediately notified school officials. And although police said the threat didn't make any specific threats to students or faculty, the school was place on a lockdown while police searched for the suspect.
"Our students here with the administration, they do go through all of those drills in cases of an emergency," said Stephanie Ferguson, a spokesperson for New Braunfels High School. "And I think today proved positive of that. We got the call and the kids (were) in lockdown within 30 seconds of getting the call."
The lockdown lasted about an hour and was lifted after the suspect was located at the Comal County Courthouse, where he was taken to the Police Department and arrested.
Police said Thursday that it was not clear what the 17-year-old suspect was doing at the courthouse, but at no time during the threat was he at the school campus.
The teenager was charged with making a terrorist threat, a third-degree felony.
The teen's name has not been released until he attends magistration proceeding Friday morning.
"We didn't worry about it because we thought it was a drill," said Elissa Lee, a student. "We have lockdown drills all the time, but then they came up and said it wasn't a drill, but I don't think anyone was really that scared, but we had to sit for a long time. "