After a week of fighting, rebels backed by Rwanda have wrested almost full control over Goma, a city of two million in the eastern Democratic Republic of Congo.

Hospitals are overflowing with the wounded, and the city morgue with the dead. Goma’s residents are beginning to emerge from their hiding places, desperately searching for water and food. And the Congolese military that was supposed to protect them has been vanquished.

On Thursday, in a yard outside Goma’s biggest stadium, rebels with the Rwanda-backed M23 militia loaded more than 1,000 soldiers they had captured into truck beds, where the men stood packed together. Most wore the uniforms they were captured in. Many of them were furious.

But the curses they spat were not directed at their captors; rather, at Felix Tshisekedi, the Congolese president, whom they accused of selling them out, and at the military commanders who had abandoned them. Their commanders, together with government officials, had left behind their vehicles, seen in videos and photographs, and boarded boats in the early hours of Monday morning as M23 arrived in the city, escaping across a moonlit lake while leaving their men to fight alone.

Many of the soldiers in the trucks had fought on, alongside armed groups known locally as the Wazalendo. But no reinforcements had been sent.

“Tshisekedi will pay for this,” one soldier shouted.

“We’ll capture him with our own hands,” another said.

“God will pay him back,” yelled another.

A commander of the 231st infantry battalion of the Congolese Army — known by its French acronym, F.A.R.D.C. — climbed down from the cabin of one of the trucks, where his seniority had earned him a comfortable spot. The captured commander, Lt. Col. John Asegi, explained that they had no choice but to surrender. M23 was taking them somewhere to give them some training, he said, adding that they would now do whatever their new masters commanded.

“If we are sent to fight the F.A.R.D.C.,” he said, “we will fight the F.A.R.D.C.”

As the M23 rebels strode around the yard preparing for the trucks’ departure, they looked more like an army with their rocket-propelled grenades, fatigues and helmets, while the Congolese soldiers looked like a tired, ragtag rebel group.

The rebels, who already control vast tracts of mineral-rich Congo, have said they plan to march to the capital, Kinshasa, nearly a thousand miles to the west, and take over the whole country.

The rebels had already handed over to Rwanda hundreds of captured Romanian mercenaries who had been fighting alongside Congolese forces.

Hundreds of civilians stood around the trucks full of soldiers, watching this reversal of roles, and getting a good look at the men who were now in charge. A dozen women and children were crying inconsolably, having just spotted their husbands and fathers among the men in the trucks.

“I don’t know where they’re taking him to,” wept Marie Sifa, who had a baby girl on her back and three other children in tow. She was from Fizi, 270 miles south of Goma, she said, and she lost everything in the attack on Minova last week. They sought shelter in a school, but they could not stay.

“We have been chased out of the school,” Ms. Sifa said, crying as if she were in mourning. “How will I survive? How will I get these children back to Fizi?”

Later on Thursday, a rebel leader, Corneille Nangaa, gave Goma’s citizens a taste of their new reality under the powerful militia — which some experts say counts 6,000 troops in eastern Congo, backed by up to 4,000 Rwandan troops.

“Go back to normal activities,” Mr. Nangaa told Goma’s residents at a two-hour news conference at a local hotel. He was flanked by men in helmets and battle gear.

But the situation in Goma, a city built around black lava streams from a nearby live volcano, is far from normal.

Dead bodies lie in the streets. Stores, supermarkets, and humanitarian agencies’ warehouses have been looted. Cholera is breaking out. People with bullet wounds — those who survived — are finally managing to get to clinics for treatment, only to find a lack of medicine and of surgical staff.

And many families who were split up as they fled have yet to find each other.

Elysée Mopanda lost track of her two children in the chaos. The rebels were holding her husband, a soldier, prisoner. The events of the past week had left her family in ruins.

“I don’t know where to go,” she said.

Wounded, harrowed, hungry, thirsty or lost, many of Goma’s residents are in an extremely precarious situation.

Most vulnerable is Goma’s displaced population, which numbers in the hundreds of thousands.

For more than a year, people have fled the rebel advance through eastern Congo’s countryside and small towns, seeking refuge in and around Goma, in sprawling, unsanitary camps that are particularly dangerous for women and girls.

As M23 closed in on these camps last week, thousands of people who had been barely surviving there fled the clashes, carrying the little they had on their heads toward Goma, which would itself soon be overtaken.

Three families who fled one of the camps just outside Goma hid in an educational center, surviving on some beans and rice they were given.

Without that kindness, “I don’t know how we would have survived,” said Furaha Kabasele, a 34-year-old mother whose youngest child is only 5 months old.

They did survive this perilous week. But they have no idea what they will do now.

For many, the most pressing need is water. The city’s water supply, as well as its power and internet, was cut during the battle for Goma, and those who had managed to save some watched it dwindle over the week. Those who had no water tried to beg it from those who did, or paid a hawker as much as $5.20 for a jerrycan that usually costs 20 cents.

As the fighting subsided, hundreds of people have ventured to the edge of Lake Kivu to collect water, adding a little chlorine to try to keep waterborne diseases at bay.

One of those fetching water on Thursday morning was Tailor Mukendi, 13, who carried two stained yellow jerrycans to the lakeshore, took off his flip-flops, and plunged into the shimmering lake. As the fighting blazed, his family had run out of water to drink.

“We couldn’t leave the house because of the gunshots and the bombs falling,” he said.

He filled the cans, and struggled to lug them out of the lake.