Witnesses said they saw the woman throw herself from the 23rd story. She landed in a sitting position on the roof of a taxi below.
"I looked up and I saw a girl that was going over the railing while another person was talking to her," said Juan Carlos Candame, who witnessed the fall. "Then she walked to the edge, went back to talk to the other person, then she turned around and she jumped."
Officials say the 30-year-old Argentine woman is being treated for internal bleeding, broken hips, and broken ribs. The taxi driver got out just before the impact.
The Associated Press contributed to this article.