Another Texas school district shut down this week after an investigation into “a credible threat” uncovered an AK-47 and a list of targets at the home of a suspect.

The Donna Independent School District said classes would be cancelled on Thursday and Friday ahead of the long Memorial Day weekend and resume on Tuesday, MyRGVNews reported.

“We’ve received a credible threat of violence that is currently under investigation,” a message to parents and staff from the district said. “In light of the recent events and in an abundance of caution, we will be canceling school district-wide classes and staff will work from home. The safety and security of our students & staff is our first priority.”

Donna is a small town in the Rio Grande Valley in the far south of Texas. It is about the same size as Uvalde, where an 18-year-old gunman opened fire on Tuesday inside an elementary school, killing 19 students and two teachers.

On Wednesday, police in Richardson, near Dallas, said they had a arrested a Berkner High School student after he was found carrying an AR-style pistol on campus.

A law enforcement source in Donna told MyRGVNews that there were two or three people involved in the shooting plot targeting a campus in the district. Investigators found the rifle and list of targeted students during a search at the home of one of them.

Police have not said if anyone has been arrested, but the case is still under investigation.

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[Featured image: Donna ISD/Google Maps]