Hundreds of healthcare workers participate in a die-in organized by Physicians for Human Rights near the United Nations building in New York to draw attention to healthcare workers killed in Syria, Oct. 29. Getty Images

About 95 percent of the doctors in Syria's largest city have left, died or been detained for their work, according to a report released Wednesday by the nonprofit Physicians for Human Rights. The Aleppo region, which has been under siege by the Islamic State group for more than a year, has only 10 functioning hospitals left because of an ongoing civil war and airstrikes in the region.

“The Syrian government is using attacks on Aleppo’s healthcare system as a weapon of war,” Dr. Michele Heisler, one of the study's authors, said in a news release. “The systematic targeting of hospitals is the biggest impediment to providing healthcare in Syria. The physicians I met want one thing -- for the bombing to stop so they can do their work.”

The civil war in Syria has killed more than 200,000 people and sent about 4 million fleeing the violence over the past four-and-a-half years, the New York Times reported. Barrel bombs and other explosives have killed more than 3,000 civilians since January 2014 and led to hundreds of other injuries, according to an Amnesty International's May report.

Intervention by Russia has also killed patients and hospital staffers, according to previous International Business Times reporting. The group counted 10 Russian attacks on Syrian health care centers through last month.

Thousands of healthcare workers left alive have fled. "They were under threat, so the easiest thing to do was leave the country," Dr. Annie Sparrow, assistant professor of global health and deputy director of the Human Rights Program at Icahn School of Medicine in New York, told Al Jazeera last year. "Even the ones who are left, it is too dangerous for them to get to work."

Aleppo once had one doctor for every 800 people, but now the ratio has skyrocketed to one for every 7,000, according to the report. There are 35 physicians working at any time, and only one-third of its original hospitals are still open. Aleppo has no psychiatrists, one cardiologist and two gynecologists.