A 90-year-old woman who was walking near Diamond Heights on Wednesday afternoon suffered life-threatening injuries when a motorcyclist struck her and fled the scene, police said.

The motorcyclist hit the elderly pedestrian at the intersection of Diamond and Duncan streets at around 3:12 p.m., according to police. The pedestrian was taken to a hospital for treatment.

Police have not identified a suspect in the case and said no arrest has been made as of early Thursday.

mbarba@sfexaminer.com