This article in the Wall Street Journal about the Youngstown State University shooting only cites two specific sources, both of whom are authority figures related to the story.
The first is Youngstown Police Chief Jimmy Hughes, who seems to be the primary source in the story. The second is Youngstown State University President Cynthia Anderson who provided a statement to the victims. Hughes' comments are scattered throughout the article while Anderson only has one. The article doesn't cite any documents, studies, or reports.
The reporter does a good job of making it clear who is speaking through the article and what exactly is being said in order to avoid confusion. The quotations are appropriately used to not provide any superfluous information, but necessary to explain the course of events following the shooting and what needs and should be known by the reader.