We watched in horror in the late evening as this story unfolded when the UN abandoned the field hospital in Port au Prince

Port-au-Prince, Haiti (CNN) — Earthquake victims, writhing in pain and grasping at life, watched doctors and nurses walk away from a field hospital Friday night after United Nations officials ordered a medical team to evacuate the area out of security concerns.

sanjayguptaCNN< .a> 5a update. we lost all generator power. sun will come up in about 30 minutes. now confident we will get all these patients through the night

The only doctor left was CNN’s Chief Medical Correspondent Sanjay Gupta. He assessed the needs of the 25 patients, but with no supplies there was little he could do.

And more people, some in critical condition, were trickling in late Friday.

“I’ve never been in a situation like this. This is quite ridiculous,” Gupta said.

With a dearth of medical facilities in Haiti’s capital, ambulances had nowhere else to take patients, some who had suffered severe trauma — amputations and head injuries. Others had suffered a great deal of blood loss, but there were no blood supplies left at the clinic.

Gupta said some might not survive the night.

He said the Belgian doctors did not want to leave their patients behind but were ordered out by the United Nations, which sent buses to transport them.

“There is concern about riots not far from here — and this is part of the problem,” Gupta said.

There have been scattered reports of violence throughout the capital.

“What is striking to me as a physician is that patients who just had surgery, patients who are critically ill are essentially being left here, nobody to care for them,” Gupta said.

Sandra Pierre, a Haitian who has been helping at the makeshift hospital, said the medical staff took most of the supplies with them.

“All the doctors, all the nurses are gone,” she said. “They are expected to be back tomorrow. They had no plan on leaving tonight. It was an order that came suddenly.”

She told Gupta, “It’s just you.”

A 7.0 magnitude earthquake flattened Haiti’s capital city Tuesday afternoon, affecting as many as 3 million people. Tens of thousands of people are feared dead.

Haiti, the poorest nation in the Western hemisphere, lacked adequate medical resources even before the disaster and has been struggling this week to tend to huge numbers of injured. The U.N. clinic, set up under several tents, was a godsend to the few who were lucky to have been brought there.

It was not known whether the medical team would return in daylight.

Retired Army Lt. Gen. Russell Honoré, who led relief efforts for Hurricane Katrina in 2005, said the evacuation of the clinic’s medical staff was unforgivable.

“Search and rescue must trump security,” Honoré said. “I’ve never seen anything like this before in my life. They need to man up and get back in there.”

Honoré drew parallels between the tragedy in New Orleans and in Port-au-Prince. But even in the chaos of Katrina, he said, he had never seen medical staff walk away.

“I find this astonishing these doctors left,” he said. “People are scared of the poor.”