Students at Houston’s C.E. King High School reportedly spent Thursday morning sheltering in place after school officials learned of a social media threat against the school.

Sheldon ISD administrators posted a notice on Facebook regarding the incident:

“Please know that all students are safe,” the district wrote in part. “The safety of our students is our top priority and we will ensure those responsible will be punished to the fullest extent of the law.”

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Officials say law enforcement secured the campus during the ordeal, and authorities lifted the lockdown at approximately 10:20 a.m.

Despite the nonissue, Thursday morning’s threat is not the first threat against a Sheldon ISD campus:

On Tuesday, a threat surfaced against C.E. King Middle School, prompting school officials to search students’ bags.

However, school officials said they did not find anything suspicious.

The district also posted on Facebook regarding that incident, asking parents to help educate their children about the seriousness of making threats, further pledging zero-tolerance for threats against students:

The district’s official statement read in part:

“Parents, please also take this time to advise your child that administrators at public schools throughout the nation, including Sheldon ISD, remain on high alert, and we will not tolerate any threatening comments, pulling of fire alarms, or any other claims of violence within the schools. This zero tolerance policy means that we are prepared to punish any student to the fullest extent of the law.”

RELATED: Lockdown lifted at HISD school after officials determined social media threat was not serious

Sheldon ISD is not the only district adhering to a zero-tolerance policy:

As C.E. King High School faced its lockdown on Thursday morning, a student in a neighboring district faced criminal charges for a threat he called a “joke.”

The 17-year-old senior at Tomball High School posted a photo of an AR-15 on his Facebook with the message “Don’t come to school tomorrow.”

Officials reportedly acted quickly to remove him, with the Tomball Police Department posting on their Facebook following his arrest:

The teen now faces a felony charge of displaying a firearm.

At this time, officials are investigating at least 21 threats of school violence across Houston, none of which they say are thought to be credible at this time.