(Riddle, OR)  --  Four children are dead following a house fire in Douglas County.  Authorities say two adults and a teenager are being treated at a Portland hospital with critical injuries.  Officials say the blaze was reported around two o'clock yesterday morning on East Third Avenue in the community of Riddle, and it killed four-year-old Gwendolyn Howell, seven-year-old Haley Maher, ten-year-old Isaiah Young and 13-year-old Nicholas Lowe.  Investigators are trying to find out what  caused the fire.