PORTLAND, Ore. (AP) — An explicit YouTube video seen by children at a middle school led to the arrest of four Portland men accused of sexually abusing two girls.

A teacher heard chatter about the video in the halls of Centennial Middle School in Gresham and found a link to it on a student’s Facebook page. The teacher recognized one of the girls engaging in sex acts with adult men as a 12-year-old seventh-grader, guidance counselor David Qualheim told The Oregonian newspaper (http://is.gd/f6gBlB ).