(Wilsonville, OR)  --  Police are searching for three teenagers accused of assaulting and robbing a transgender person in Wilsonville.  The Clackamas County Sheriff's Office says the teens approached the victim on a path near the Willamette River across from the Boones Ferry Boat Launch on Tuesday and used a transgender slur against them.  They then left and returned about 45 minutes later and stole the victim's cellphone and punched them at least twice, causing them to fall into the river.  Another person swimming in the river helped the victim back to shore.  Anyone with information is urged to contact police.