KHARKIV, Ukraine (AP) -- Ukrainian forces fought Saturday to hold off a Russian advance aimed at capturing an eastern industrial region along with Ukraine's last holdout in the southern city of Mairupol, where fighters and civilians hiding under a heavily damaged steel mill endure harrowing conditions.
The United Nations continued trying to broker an evacuation of civilians from the sprawling Soviet-era plant and other bombed-out ruins of Mariupol, a port city which Russia has sought to capture and subjected to heavy bombardment since it invaded Ukraine more than nine weeks ago.
There are up to 1,000 civilians at the Azovstal steelworks, according to Ukrainian officials, who have not said how many fighters remained in the only part of Mariupul not occupied by Russian forces. The Russians put the number of Ukrainian soldiers at the plant at about 2,000.
Video and images shared with The Associated Press by two Ukrainian women who said their husbands are among the fighters there showed wounded men with stained bandages in need of changing; others had open wounds or amputated limbs.
A skeleton medical staff was treating at least 600 wounded people, said the women, who identified their husbands as members of the Azov Regiment of Ukraine's National Guard. Some of the wounds were rotting with gangrene, they said.
In the video the women shared, the wounded men, who are not identified, tell the camera they eat once a day and share as little as 1.5 liters (50 ounces) of water a day among four. Supplies inside the blockaded are depleting, they said.
The AP could not independently verify the date and location of the footage, which the women said was taken in the last week in the warren of passageways beneath the steel mill.
One shirtless man spoke in obvious pain as he described his wounds: two broken ribs, a punctured lung and a dislocated arm that "was hanging on the flesh."
"I want to tell everyone who sees this. If you will not stop this here, in Ukraine, it will go further, to Europe," he said.
In other developments:
-- Russian Foreign Minister Sergey Lavrov said in an interview that Russian and Ukrainian negotiators talk "almost every day." However, he told Chinese state news agency Xinhua that "progress has not been easy."
-- A former U.S. Marine was killed while fighting alongside Ukrainian forces, his family said, in what would be the war's first known death of an American in combat. The U.S. has not confirmed the report.
-- Two buses that were headed to the town of Popasna in eastern Ukraine to evacuate residents were fired upon, and contact with the drivers was lost, Mayor Nikolai Khanatov said.
-- Russian air-defense forces detected a Ukrainian military plane over Russia's Bryansk region and tried to repel the aircraft. Two shells fell on a village, regional Gov. Alexander Bogomaz said. No one was injured, but an oil terminal suffered some damage, Bogomaz said.
Getting a full picture of the unfolding battle in the east has been difficult because airstrikes and artillery barrages have made it extremely dangerous for reporters to move around. Both Ukraine and the Moscow-backed rebels fighting in the east also have introduced tight restrictions on reporting from the combat zone.
But Western military analysts suggested that Moscow's offensive in the eastern Donbas region, which includes Mariupol, was going much slower than planned. So far, Russia's troops and the separatist forces Moscow has backed in the region since 2014 appeared to have made only minor gains in the month since Moscow said it would focus its military strength in eastern Ukraine.
Numerically, Russia's military manpower vastly exceeds Ukraine's. In the days before the war began, Western intelligence estimated Russia had positioned near the border as many as 190,000 troops; Ukraine's standing military is about 200,000, spread throughout the country.
In part because of the tenacity of the Ukrainian resistance, the U.S. believes the Russians are "at least several days behind where they wanted to be" as they try to encircle Ukrainian troops in the east, said a senior U.S. defense official who spoke on condition of anonymity to discuss the American military's assessment.
The British Defense Ministry offered a similar conclusion in its daily assessment of the war, saying it believes Russian forces in Ukraine are likely suffering from "weakened morale," along with a lack of unit-level skills and "inconsistent air support." It did not say on what basis it made the evaluation.
With plenty of firepower still in reserve, Russia's promised offensive still could intensify and overrun the Ukrainians. Overall, the Russian army has an estimated 900,000 active-duty personnel. Russia also has a much larger air force and navy than Ukraine and possesses tactical nuclear weapons.
Ukrainian President Volodymyr Zelenskyy acknowledged as much in his nightly address.
"If the Russian invaders succeed in realizing their plans, at least in part, they will still have enough artillery and aircraft to destroy the entire Donbas. Just as they destroyed Mariupol,'' he said.
"The city, which was one of the most developed in the region, is simply a Russian concentration camp in the middle of ruins," Zelenskyy said.
In Mariupol, around 100,000 people were believed to still be in the city with little food, water or medicine. U.N. spokesman Farhan Haq said the organization was negotiating with authorities in Moscow and Kyiv to create the conditions for safe passage.
Ukraine has blamed the failure of numerous previous evacuation attempts on continued Russian shelling.
For those who are in steel plant, a vast underground network of tunnels and bunkers has provided safety from airstrikes. But the situation has grown more dire after the Russians dropped "bunker busters" and other bombs on the plant, the mayor said Friday.
The women who said their husbands are in the steel plant as part of the Azov Regiment said they feared soldiers will be tortured and killed if they are left behind and captured by the Russians. They asked for a Dunkirk-style mission to evacuate the fighters, a reference to the World War II operation launched to rescue surrounded Allied troops in northern France.
"We can do this extraction operation ... which will save our soldiers, our civilians, our kids," Kateryna Prokopenko, 27, said, speaking to the AP in Rome. "We need to do this right now, because people -- every hour, every second -- are dying."
The Azov Regiment helping to defend the steel plant has its roots in the Azov Battalion, which was formed in 2014 by far-right activists at the start of the separatist conflict in eastern Ukraine. Russian officials have referred to the regiment's past while attempting to justify its activities in eastern Ukraine.
Despite the intensity of the fighting in the east, some Ukrainians tried to make their way back to the embattled region, going against the flow of the nearly 5.5 million people who have fled the country since Russia invaded.
"Everything is there. Our roots are there," a 75-year-old man intending to cross the front-line from Zaporizhzhia with his wife to reach his home in Donetsk. "Even people from Mariupol want to go back."