(Estacada, OR)  --  Estacada school district officials say the start of school this morning was delayed following a bomb threat.  Authorities say the threat was called in around 5:45 yesterday afternoon, claiming a bomb had been placed at Estacada High.  A bomb squad searched the school grounds and buildings and found nothing suspicious. The school was given the 'all-clear' just before 9:00 a.m.