The 13-year-old middle school student was being held at the Porter County Juvenile Detention Center, and investigators do not believe the boy had access to weapons, according to the Valparaiso Police Department.
Valparaiso Police said in a statement on Thursday that the boy allegedly told Siri, "I am going to shoot up a school."
The digital assistant then created a list of several Valparaiso schools nearby.
However, the student made no direct threat to a specific person, school or school system.
"The threat is not believed to be credible at this time; however, these types of communications are taken very seriously by the Valparaiso Police Department and our community," the Valparaiso Police Department said in its statement. "We continue to work with the Valparaiso Community Schools to ensure the safety of the students and staff."
He allegedly posted the screenshot on Thursday.
The incident was reported to police in nearby Chesterton by the boy's social media contacts.
The Associated Press contributed to this story.