The Harford County Sheriff’s Office charged a student for allegedly making threats to a school last week, marking the second such arrest of a Harford County Public Schools student in a week.

The student was arrested and charged with making a threat of mass violence and possession of illegal ammunition after the student resource officer at Fallston High School was made aware of the threats, according to a Friday news release from the sheriff’s office.

The release noted that the investigation is still ongoing and that other individuals could be charged.

According to the sheriff’s office in a Wednesday news release, another threat against a Harford school was posted on social media by a student early that morning. The 2:20 a.m. post on Snapchat said, “shooting up the school, this is a threat,” according to the release.

A student was charged with making threats to commit an act of mass violence, but the release did not say which school was involved.

The arrests follow a slew of threats made toward public schools in Harford County. On Wednesday, the sheriff’s office said that the previous week alone, deputies had investigated 11 threats to schools. The office posted Friday that it had since investigated five more threats. The school system received three threats on just Wednesday.