After School, a smartphone app used by high schoolers to post their thoughts and ideas anonymously and broadcast them to others at school, has been pulled from the Apple Itunes store for the second time since its November launch, according to the Macomb Daily News.

After School was cited for violating the “personal attacks” and “objectionable content” categories of Apple’s App Store Guidelines, according to Re/code.

The App was the center of controversy this week after it was used to make anonymous threats of violence at Brandon High School, in Clarkston, Michigan last week. A series of anonymous postings threatened to carry out an attack against students. “Tomorrow I’m gonna shoot and kill every last one of you and its going to be bigger than Columbine just wait,” one of the postings read. In total, 17 threats were made, posting images of heavily armed men on the network. Spooked parents kept their children home from school the next day as authorities worked to hunt the culprit down.

As with many “anonymous” apps and forums, messages can be posted “anonymously” on the app — but users divulge their Facebook account information to the publisher. Police were able to track down the sender of the messages by Facebook account addresses that were needed to access the app and trace them to a 17-year-old student. But first, they ran into  barriers — including finding the developer’s contact information to serve a search warrant from the Federal Bureau of Investigation.

Jacob Michael Young, a senior, was traced as the source of the threats. His attorney says he may be dealing with some “emotional problems” and viewed his action as activism against a spate of bullying that was occurring on the app. He is being charged with making terroristic threats.

His attorney, Deanna Kelley, said that trying to make a statement about the app and raise awareness that it’s being used for online, anonymous bullying.

“He was upset about bullying on the app and nobody was doing anything about it. This was his explanation to police and it went horribly wrong.”

“This is a 17-year-old kid,” she said. “These apps are so dangerous. Kids aren’t thinking about who reads what they write and how they respond to it.”

After a spate of similar incidents, Apple had the app removed from the App Store on Dec. 4 “so the developers could make changes to make it safer for students and it went back online later that day.” School administrators in Lubbock, Texas even sent home a memo warning parents about the dangers of the app. Recently, in Richmond, Ohio, a similar anonymous-sharing app was used to make threats, forcing the school to go into lockdown mode and causing administrators to search over 700 students.