BALTIMORE -- A disturbing video we first aired Wednesday night has gone viral. It shows hospital staffers in Baltimore dropping off a woman on a cold city street. The video has sparked outrage, and raised concerns about the treatment of patients at hospitals across the country.

In the video, four hospital security guards are seen pushing a red wheelchair away from a bus stop. They had just left a patient in the freezing temperatures, and all she had on was a hospital gown and socks.

"So you all are just going to leave this lady out here with no clothes on," asked Imamu Baraka, a passerby who started recording the scene with his cellphone.

Imamu Baraka shot video of a woman being wheeled to a bus stop in a hospital gown CBS News

"She's in the heart of downtown Baltimore with no clothing on, vulnerable, fully exposed, literally, I became enraged," Baraka now says. He called 911 and says medics ended up taking the patient back to the same hospital.

The University of Maryland Medical Center apologized Thursday and promised a thorough investigation.

"We feel comfortable in the statement that what you saw in that video is not a process that would occur with any frequency at all," said Dr. Mohan Suntha, president and CEO of the University of Maryland Medical Center.

There is no national database that tracks so-called "patient dumping" incidents. They often occur because a patient lacks insurance or financial resources.

"The legal requirement is that the hospital make sure that a person is fully treated," said Catherine Lhamon, chair of the U.S. Commission on Civil Rights.

"What I see from that video is a person who was not stabilized, is a person who needed further care. Clearly there was more that that hospital needed to do."

To protect her privacy, we are not identifying the woman. But on Facebook, her mother called the video "horrifying". She says her daughter is with her family and getting medical treatment, but not at the hospital from the video.