The 18 Americans who were aboard a hantavirus-stricken cruise ship have returned to the U.S. and are now in quarantine.

A gunman opens fire at passing cars along the Charles River near Boston.

And, a CBS News exclusive. Kirk Moore, an Oklahoma high school principal, took a bullet tackling a gunman in his school's lobby. He told CBS News what he did was "just instinct" and said he didn't even realize he'd been shot at first.