(Sidon, Lebanon-AP) -- An American missionary who trained at Chicago's Moody Bible Institute was shot to death at the Lebanese clinic where she worked as a nurse. The incident was believed to be the first targeted killing of a U-S citizen in Lebanon in more than a decade. A gunman fired three bullets into 31-year-old Bonnie Penner's head yesterday morning. A spokeswoman at Moody says Penner studied there from 1993 to 1996 and completed a degree in International Ministries in 2000. The Lebanese center's director says there were no threats before the killing and the motive wasn't known. The clinic provides medical care and help to local people and Palestinian refugees in a nearby camp in southern Lebanon.