ARGENTINE TOWNSHIP, Mich. (AP) — Three teenage boys are charged with conspiring to shoot people at two Michigan schools.

Argentine Township Police Chief Dan Allen says the alleged plot was uncovered more than a week ago in the Linden district, 20 miles south of Flint. The teens are in custody.

Allen said Saturday that the group had “specific targets in mind” at Linden High School and Linden Middle School. He says the investigation revealed the threat was “serious and credible.”

The three teens were arrested on Oct. 29 and never reached school property. They’re charged with conspiring to commit first-degree murder.

Allen says the oldest, 18-year-old Ryan Stevens, is a former Linden student. It’s not known if he has an attorney yet. The other suspects are 15 and live outside the school district.