Pittsburgh police joined the search for a 17-year-old boy, saying it is "out of character" for him to have not contacted his family since Friday.

Friends say they last saw Joseph Harris at 9 p.m. Friday boarding a bus and saying he was going to meet someone named "G."

Police say the boy isn't known to have a friend by that name and that his cell phone has been turned off since Friday, too.

Harris' father, also named Joe, says his son recently was upset about a girl and may also be afraid after learning he'd face school discipline for skipping a few classes recently.

Police Lt. Kevin Kraus says authorities are concerned because the missing teen "isn't a kid who showed any signs or hints of trouble."