It started with two students at St. Paul’s School for Girls being sent sexually explicit material through a social networking site. Then Bel Air’s John Carroll School notified parents that the same creep had contacted two of its (female) students. And now we’re hearing reports that (male) students at The Gilman School have been contacted by the same person.

On various social media sites, the predator in question goes by various names, including J.P. Smith, Brian Pond, JPL42, and MatLax. (It’s unclear how investigators know that all these handles belong to the same person, but apparently the Baltimore Police are on the case.) He’s contacted students via Facebook, Instagram, Snapchat, and Vine. He contacted more than 50 students at St. Paul’s, and a number at other local private schools.

“Many, if not most, of us use some form of social media on a regular basis, and we all need to help each other—our students, particularly—to be responsible, safe digital citizens,” Henry Smyth, Gilman Headmaster, wrote in a letter to parents. Smyth also reminded students to take a few precautions, including not “friending” anyone that they don’t know personally; not posting any material “that they would not want their parents or grandparents to see”; and making sure to notify a parent and/or school advisor if they receive any suspicious contact from someone online.