GEOFF BENNETT: A new report funded by the State Department paints a dire picture of the humanitarian situation in Darfur in Western Sudan.

Nearly five months ago, the Sudanese military and insurgent Rapid Support Forces, or RSF, started fighting each other for power.

The U.N. says at least 4,000 people have died.

Violence quickly spilled into Darfur, where elements of the RSF were accused of genocide 20 years ago.

As Nick Schifrin reports, history appears to be repeating itself.

NICK SCHIFRIN: The aftermath of airstrikes, the echo of gunfire, and the frightening flames of civil war have engulfed Sudan's cities.

Just last week in the capital, Khartoum, a massive fire burned near the airport.

There's no safety for the living and no dignity for the dead.

Civilians are dying so quickly,graves are left unmarked.

And now the power struggle between Sudan's armed forces and the Rapid Support Forces, or RSF, has reignited ethnic conflict in Darfur, a Western region the size of Spain.

NATHANIEL RAYMOND, Yale School of Public Health: It is ethnic cleansing.

And it is ethnic cleansing that right now is occurring.

NICK SCHIFRIN: Nathaniel Raymond is the executive director of the Humanitarian Research Lab at the Yale School of Public Health.

His team works on the State Department-funded Sudan Conflict Observatory to expose the atrocities of war that might otherwise go unreported.

NATHANIEL RAYMOND: Cell phone connectivity and Internet connectivity has been knocked out, in some cases, intentionally, as we have documented, by the RSF.

And so our work is, unfortunately, the only game in town in many cases to be able to corroborate what is happening.

And that is done through a combination of satellite imagery, open-source reporting and also thermal sensors from NASA.

NICK SCHIFRIN: Their new report from Darfur's largest city, Nyala, shows damage to a market, a mosque, a military hospital, and a prison.

Last week, a local journalist from Nyala posted these photos of what appeared to be a single incident where dozens died.

We spoke to one of the victims who survived.

Mahala Adam has now fled to East Darfur.

MAHALA ADAM, Victim (through translator): A little girl called Huda her face was split down the middle.

Another neighbor's head was severed.

I started screaming when I saw my aunt's head had exploded.

I kept screaming for help.

My aunt's family has been torn apart.

I passed out.

That's the last thing I remember.

No one came to help, no government, no military, no Rapid Support Forces.

Absolutely no one came.

NATHANIEL RAYMOND: We have seen an alleged massacre of almost 30 people, including from five families, at the Teiba Bridge, reportedly, where they were killed by a stray missile.

And so the situation is, is that both forces are now moving into civilian areas, occupying civilian homes, and firing at each other in close proximity.

In the middle of this battle are civilians.

NICK SCHIFRIN: Do you believe exposing what's happening can protect the people on the ground?

NATHANIEL RAYMOND: At this point, we are conducting early warning.

That turns into autopsies.

We are trying to warn.

And when the warning goes on heated, we are trying to document the destruction of entire communities.

NICK SCHIFRIN: In the 2000s, government-backed Janjaweed militias in Darfur brutally crushed an uprising and killed hundreds of thousands of non-Arabs.

The Janjaweed gave birth to the RSF, which, today, with other Arab militias in the same place, is behind the new violence in Darfur.

NATHANIEL RAYMOND: We are concerned that Nyala is a preview is a coming attraction of what happens next.

We are talking hundreds of thousands of people, the most vulnerable people on the planet, who have really at this point no protection force between them and RSF, which has clearly shown, like the Janjaweed from which they are descended, that their intent is to liquidate, prioritizing men, but also with sexual gender-based violence against women, to liquidate non-Arab people in Darfur.

NICK SCHIFRIN: And the violence has targeted Sudan's healers.

As many as three-quarters of health care facilities have been destroyed.

Dr. Yasir Elamin is president of the Sudanese American Physicians Association.

DR. YASIR ELAMIN, President, Sudanese American Physicians Association: The situation in Sudan in terms of health care is in near complete collapse.

The majority of hospitals and health care centers are out of service in Khartoum, the capital, where most of the health care services are concentrated to begin with.

And that's also the case in Darfur, the rest of the country.

What that means is, A, people who get injured as a result of the war, they don't get the care that they need.

And those who get other medical conditions, whether heart attacks, whether need their diabetes to be managed, a woman wants to deliver, a kid who needed vaccination, all these services are mostly nonfunctional now.

In Sudanese social media groups, people are exchanging tips on how you can deliver a woman at home.

So, it's in a very, very bad situation.

NICK SCHIFRIN: The international community has said that it is getting supplies into the country, more today than they were a few months ago.

But are those supplies reaching hospitals?

Are they reaching the people who need them?

DR. YASIR ELAMIN: So, the situation has improved, as you point out, but it continues to be terrible, in the sense that there is a mismatch between what's actually delivered to Port Sudan, which is the key port to the country, and what's actually delivered to the end user.

And this is due to safety reasons -- so, it's not safe to move stuff around most of the country -- and also due to a nonfunctional government that is incapable of delivering aid to those who need it most.

And, finally, I also think the international aid agency, whether the American, whether the U.N. one, have been really reluctant for so many reasons to work with the local community.

NICK SCHIFRIN: But zoom into Darfur.

You're opening up a new clinic on the border between West Darfur and Chad.

What's the humanitarian situation there?

DR. YASIR ELAMIN: Hundreds of thousands have left Darfur, went to church.

The situation there is particularly tough, because it's taken this ethnic flavor to it.

And it's kind of tragic, in the sense that the RSF was formed originally to help it suppress the rebellion in Darfur, and now it turns against the army.

But the bottom line, the RSF was trained not to respect human rights, to kill on basis of ethnicity, and to use sexual violence as well.

And that has been really seen mostly in Darfur, where there are kind of very credible reports that there has been killing based on ethnicity, there has been indiscriminate killing of civilians in Al-Junaynah, the capital of West Darfur.

Basically, you have no health care services.

NICK SCHIFRIN: And you mentioned sexual violence.

Is that one of the most brutal aspects of this conflict?

DR. YASIR ELAMIN: Absolutely.

So Sudan has known sexual violence as a tool in war.

Last week, there were reports of women being sold.

So, we're seeing certainly kind of a resurrection with these crimes that we have seen in the past in Darfur.

NICK SCHIFRIN: We have been interviewing people in Darfur, and they describe these harrowing scenes of the wounded not being able to reach the hospitals and dying on the way, and exactly what you said before, people who need routine medical care simply unable to get it and dying for that reason.

Overall, the level of crisis there seems like it's getting worse.

DR. YASIR ELAMIN: Absolutely, it's getting worse.

As I said, you have West Darfur, no health care services.

Now the violence has spread to South Darfur, Nyala.

The bombing has included also other, different parts of Darfur.

So, it's -- I think, in Darfur, particularly, the worst is yet to come, because I think the social fabric there, in Khartoum, you have RSF and the army fighting.

But, in Darfur, I do think that we're seeing evidence that's now spread into the larger society, ethnic tensions in Darfur that can open the door to widespread violence.

NICK SCHIFRIN: There are about to be as many as five million people displaced.

How much of a threat is that massive number to the country and to the region?

DR. YASIR ELAMIN: First of all, this is creating a difficult security situation within Sudan itself.

It's putting pressure on all the services and other cities that are not equipped to deal with these large numbers.

And, overall, I think, if the war escalates, and we see people leaving Sudan, and the country disintegrates, I think it's going to have a huge impact across the continent, which is already suffering a lot from multiple wars.

NICK SCHIFRIN: Dr. Yasir Elamin, president of the Sudanese American Physicians Association, thank you very much.

DR. YASIR ELAMIN: Thanks for having me.