Kathy Dixon is a co-agent at the company and said she was in a back room when the car smashed into the building just before 11 a.m.
"I just heard a loud, horrendous crash," she said.
Dixon said the company's office manager was at a desk near the front window and was hit and pinned underneath the car.
"I called out her name and she didn't answer," Dixon said.
Renton Fire Department Captain Doug McDonald said firefighters had to knock out part of a brick wall and a window to get the woman out from under the car and rubble.
Medics performed CPR on 60-year-old Kaye Hall of Buckley, but she died at the scene.
The 80-year-old woman who was driving the car was not hurt.
Renton Police Commander Clark Wilcox said the woman was trying to turn south onto Logan Avenue from Airport Way and just continued turning sharply and crashed into the building.
He said the woman is upset, a little confused a not sure exactly what happened.
Investigators have cordoned off the scene at 45 Logan Avenue South while they collect evidence.