A third person was pistol-whipped before the hostages were freed at the Nordstrom Rack clothing store at the Promenade at Howard Hughes Center in the West Chester section, the Los Angeles Times reported.
The gunmen fled with an undetermined amount of money, investigators said.
The stabbed woman's injuries were not life-threatening, the Times report said.
Police said the robbers took the hostages, all employees of the store, and forced them into a storage room. The hostages were freed about 3:30 a.m. Friday.