ADEN, Yemen » Rooftop snipers have emptied the streets of this dusty, seaside city and swelled its hospitals and morgues.

Weeks of fighting between armed groups have left nearly 200 people dead and the city starved of water, fuel and electricity. Hospitals struggle for anesthetic and dressings. Barefoot, nervous teenagers with matted hair and guns mind checkpoints on the treacherous roads. Gunbattles sweep across the city, while residents lie low and worry that Aden’s suffering will only increase.

"The war of hunger has not started — yet," said Ali Bamatraf, a grocer with dwindling stocks, standing among empty food boxes that would not soon be replaced.

As war engulfs Yemen, no place in this beleaguered country has suffered as severely as Aden, a southern port city captive to ferocious and deadly street fighting for the better part of a harrowing month. Foreign navies patrol its waters and warplanes circle above, blockading a city that is steadily crumbling under reckless fire from tanks and heavy guns.

"Damaged. Ruined," said Faris al-Shuaibi, a professor of English literature at Aden University, searching for the words to describe a beaten-up neighborhood around him. "Everything is destroyed."

The clashes began in mid-March as a feud between forces allied with Yemen’s elite political actors: southern fighters loyal to President Abed Rabbo Mansour Hadi, who had retreated to Aden after being driven from the capital, Sanaa, against Houthi militiamen and security forces allied with Ali Abdullah Saleh, Yemen’s former leader.

Weeks later, the war in Yemen has spread and become far more complicated. Saudi Arabia unleashed an air offensive last month that has failed to stop the Houthi advance. Saudi officials are threatening a ground invasion, seeing the hand of Iran, their regional nemesis, behind the Houthis, whose leaders follow an offshoot of Shiite Islam.

For many residents of Aden, each day of war has only simplified the conflict, reducing it to an existential fight. After Hadi and most of his loyal fighters quit the city, residents dusted off personal weapons and formed their own units to fight the advance of the Houthis and their allies — the latest northern invaders, they say, seeking to dominate the south.

North and South Yemen were separate countries until 1990, and fought a brief civil war four years later. For decades, southern grievances over ill treatment by the rulers in the northern capital, Sanaa, have festered, escalating in recent years into a movement openly calling for secession.

Al-Shuaibi was among thousands of people protesting peacefully a few months ago in Aden for an independent state, in a square adorned with pictures of southerners who died in wars and at the hands of Saleh’s security forces.

On Thursday, he was back in the streets, with a gun, preparing to join other residents fighting in the central district of Al Mualla.

The local militias are loosely organized, dominated by young men focused on securing their own neighborhoods, said Jamal Khulaqi, a 25-year-old Yemeni-American from Buffalo, New York, who said he was helping with relief efforts in the city. Most lacked training and weapons apart from AK-47s.

Their opponents are mostly security men loyal to Saleh, known for their repression back when they were in power. Now, as militiamen, residents say, they are unrestrained and more brutal. "They are bombing innocent people, families," al-Shuaibi said.

The Houthis, fighting all over the country, are a smaller part of the force in Aden, their ranks filled with many teenagers, and even some children. Some of the young Houthis who had been captured seemed filled with religious zeal, and said they had been told they were going to fight al-Qaida in Aden, the Sunni extremists the Houthis regard as their principal foe, al-Shuaibi said.

"There is no al-Qaida here," he said.

The city has been carved up into sectors guarded by fighters with guns slung over their shoulders, drained by the stresses of war but still full of swagger. One fighter, Mohamed Saleh Salem, 38, called the local fighters "ferocious" and vowed that the Houthis would not advance, while adding that he had not had a bath in days.

The Houthis and their allies, armed with tanks and other heavy weapons, have captured several strategic areas, including a coastal road. But their hold on the city remains shaky, and they are vulnerable to repeated attacks by the local groups, fighting in familiar neighborhoods.

The Houthi forces respond savagely to any assault, Khulaqi said. "When someone shoots at them, they fire on buildings," he said as he drove a friend through the city’s checkpoints, to catch the only bus still shuttling people out of Aden and across the country to the Saudi border.

As dangerous as it is to travel outside the city, it has become deadly to stay. Volunteer medics said that at least 198 people had been killed and nearly 2,000 people injured in the city since March 25. The estimate was probably conservative: Ambulances have not been able to reach people in neighborhoods with the heaviest fighting, said Khadeja bin Bourek, a volunteer aid worker, who said there was also a shortage of medics at government hospitals.

Valerie Pierre, the project coordinator for Doctors Without Borders in Aden, said an average of 15 to 20 patients arrived every day at a hospital where the group is working and living, most of them gunshot victims. The group had just received its first shipment of medical supplies, by boat from the tiny East African nation of Djibouti, across a narrow strait from Aden, but still had only a third of the supplies they needed.

Pierre, a midwife, had arrived in Aden in January, finding a "beautiful city, a very historic place." Now, she and the other doctors were sequestered, listening to gunbattles, sometimes distant, sometimes just outside the hospital walls.

"I am full of adrenaline, so I am still running, still motivated," she said. "It is very scary."

Elsewhere in the city, residents were hauling water in buckets because water tanks supplying at least four districts had been destroyed or cut off by the fighting. In many places, only a few hours of electricity was available every day. Only local neighborhood stores were open, and by 7 p.m. the streets were empty, except for the fighters.

Saudi airstrikes have mostly targeted the outskirts of the city, in an attempt to cut off the supply lines of the Houthis and their allies. There also appears to have been shelling from warships, though no one seemed to know for sure.

"Aden is almost the only city in Yemen to be attacked by air, sea and land," said Nashwan al-Othmani, a resident.

The siege has left little time to think about the political arguments dividing the country. No one seems to be clamoring for the return of Hadi, whom the Saudis have vowed to restore as president.

"There are many that criticize Hadi," al-Othmani said. "There are many that accuse him of bringing the struggle to Aden, and then leaving."

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