San Marcos CISD, which started classes on Aug. 24, received word of a "potential threat" on Sept. 2. The district released a statement about the incident.

"At about 11:15 a.m. on Tuesday, September 2, 2015, San Marcos High School received information about a potential threat," the district's statement said. "The high school administration immediately called for a shelter in place as a precaution while the high school administrators and [school resource officers, or SROs] worked to ensure that a threat did not exist  All was cleared within 15 minutes.  At no time were students in danger or at risk.  SMHS’ administrators and SROs determined the information proved to be false."

"Although this was a low-incident matter, San Marcos CISD will always ensure precautions are taken to keep our students and staff safe," the statement said.