Three teenage girls who allegedly sent nude or semi-nude cell phone pictures of themselves, and three male classmates in a western Pennsylvania high school who received them, are charged with child pornography.

Police in Greensburg, about 30 miles east of Pittsburgh, say the girls are 14 or 15 and the boys charged with receiving the photos are 16 or 17. None are being identified because most criminal cases in Pennsylvania juvenile courts are not public.

Police say Greensburg Salem High School officials learned of the photos in November when a student was seen using a cell phone during school hours, which violates school rules.

The phone was seized and the photos were found on it. When police investigated, other phones with more pictures were seized.