POND CREEK, Okla.—Three people from Nebraska have been killed in a plane crash in northwestern Oklahoma, authorities said. The pilot William Lauber, 58, of Milford; passenger Christine Lauber, 58, of Milford; and passenger Ragan Lauber, 21, of Lincoln, died in the crash about 4:30 p.m. Thursday, the Oklahoma Highway Patrol said in a statement. Witnesses…