A 29-year-old Anchorage woman was killed early Sunday when she jumped out of a van still in motion, police said.

Diana Knapp suffered head and neck injuries. Police said they found her dead and the van pulled over at the East Anchorage intersection of Bragaw Road and Ninth Avenue at 3:55 a.m.

She was one of three passengers in the van when she jumped out for unknown reasons, police said. Witnesses told police that drugs were involved. An autopsy will be done and toxicology tests will determine whether she was impaired and by what, said police spokesman, Lt. Dave Parker.

There's no indication that she was pushed or died from anything other than jumping from the moving vehicle, Parker said. The other people in the van all cooperated with police, he said.

Knapp had a difficult life. Court records show that she's had a number of run-ins with the law for minor crimes including disorderly conduct and misdemeanor assault. Relatives have gone to court for protective orders against her. Last year, she was put under court-ordered guardianship, a court record showed.