The woman, who was in her 30s, became pinned between the platform and scaffolding about 8 a.m. at a construction site below the Leavey Center.
When emergency workers arrived, her co-workers were performing CPR, said Pete Piringer, a spokesman for the D.C. Fire/EMS department. She was rushed to George Washington Hospital, where she died.
She was taken to George Washington instead of the closer Georgetown University hospital because emergency workers determined that it has better resources to treat her, authorities said.
Police have not yet released her name.