FOUR DEAD, ONE MISSING AFTER PITTSBURGH-AREA HOUSE EXPLODES

Four people are dead and one is missing after a house apparently exploded Saturday morning in a Pittsburgh suburb.  The fire that followed destroyed two other homes.  One person is hospitalized in critical condition while two others were treated and released.  It happened shortly before 10:30 a.m. Saturday in the borough of Plum, about 20 miles east of downtown Pittsburgh.  Eighteen fire departments responded to the disaster.  The cause is under investigation.