JOHNSTON, Iowa  —  A group of overseas hackers have posted the Johnston school directory online including the name, grade level and address of thousands of students and their parents’ phone numbers.

The group “Dark Overlord” claimed credit on Twitter Thursday for hacking into Johnston school information and making text message threats to Johnston parents.  Those threats lead the school district to cancel classes on Tuesday.  Police now say none of the threats were credible.

Johnston Schools sent a message to parents Thursday evening saying they expected the directory information to be released online.  Johnston Police say the release of the information does not pose any credible physical threats to students or their families.  However they are warning parents to have a “heightened sense of awareness” for the time being.

Meanwhile West Des Moines Police say they have determined who is responsible for “copycat” threats made at their schools this week.  The name of the suspect hasn’t been released.  West Des Moines did not cancel classes.

This is the complete message sent out by Johnston Schools:

“A group named “The Dark Overlord” has taken responsibility for this cyber-crime and today, as expected, they have posted Johnston school directory files on a publicly accessible website. The information posted includes student names, addresses, and telephone numbers.

The Johnston Police Department believes these cyber-threats do not pose a credible, physical threat to Johnston students or staff.  However, since names, addresses and telephone numbers of students are now accessible on a public website, it is advisable for parents and students to operate with a heightened sense of awareness.  Attached to this release is a list from the Johnston Police Department about ways you can monitor your online security (JPD Online Security).

The Dark Overlord is a hacking group that extorts victims for ransom payments in bitcoin. They have targeted many different businesses and organizations in multiple states over the last year or so. The list of those impacted include: Netflix; numerous health care providers; movie and television studios; private manufacturers; and, most recently, several school districts.

The identities of the hackers involved with The Dark Overlord group are unknown, but local, state and federal law enforcement officials are aware of their presence around the country due to the cybersecurity threats they pose. The Johnston Police Department is one such agency with an active, ongoing investigation into the criminal activities of this group.

The Johnston Community School District is taking this cyber-breach very seriously. District officials continue to cooperate with law enforcement as they investigate the matter.

The safety and security of our students and staff is our top priority. Our goal is to provide a safe, nurturing and educational environment for all children.”