SANAA, Yemen (AP) -- In Yemen's third largest city, residents are battling back against a months-long siege by Shiite rebels, armed by airdrops of weapons by planes from the Saudi-led coalition, with hundreds killed and food, water and medicines running short in a potentially pivotal battle in the country's protracted civil war.
The Shiite rebels, known as Houthis, have surrounded the city of Taiz for months, shelling neighborhoods and battling with the local fighters. Anti-Houthi forces backed by a Saudi-led coalition are trying to advance from further south, fighting their way toward the city to break the siege.
If the Houthis lose at Taiz, which lies on the border between northern and southern Yemen, it could be a major turning point in the war. It would cement the Houthis' loss of the south, reducing their areas of control to the capital, Sanaa, and their strongholds in the far north, along with some areas in the center with little strategic significance. That could force them into negotiations with the internationally recognized government, led by President Abed Rabbo Mansour Hadi.
Residents in the city of some 250,000 say more than 1,600 civilians have been killed in the siege since March, largely by Houthi shelling. Electricity is largely cut, water supplies are low and food and other supplies have to be smuggled in, they told The Associated Press.
"The shelling is indiscriminate, on houses and schools," said Samir al-Mekhlafi, a 35-year-old engineer in Taiz. "We go to sleep unsure if we'll wake up alive. And then we wake up alive without guarantee we'll be alive when evening comes."
Taiz is considered Yemen's cultural capital, with one of the country's main universities and a relatively cosmopolitan, politically minded population -- it was a major center, for example, in the 2011 pro-democracy uprising that eventually led to the removal of longtime autocrat Ali Abdullah Saleh.
Now, Houthi rebels hold the university, located on elevated ground on the western outskirts, and rockets and tank fire from there hammer residential neighborhoods.
"Taiz is being shelled from inside Taiz University. I swear to God this is the last thing we could have expected," al-Mekhlafi said.
The U.N. Office for Coordination of Humanitarian Affairs on Tuesday sounded alarm over the humanitarian situation, saying the Houthis are "blocking supply routes and continue to obstruct the delivery of urgently needed humanitarian aid and supplies" into the city. Hospitals are overwhelmed with wounded and face shortages of medicine, it said.
The fierce siege is likely intended as a warning to the anti-Houthi forces about what they will face if they eventually try an assault on Sanaa, said Abdul-Ghani Al-Iryani, a prominent Yemeni political analyst.
The Houthis want "to show the horror of the war in Taiz to send a message to the other side: If Taiz is the way it is, how will Sanaa be?'"
"The battle for Sanaa will be a lot more gruesome, longer, and more difficult on all angles," he said.
Farea al-Muslimi, a visiting scholar at the Carnegie Middle East Center with a focus on Yemeni and Gulf politics, said the anti-Houthi coalition appears to want to take control of Taiz and force the Houthis into making a deal over Sanaa.
The Houthis, based in the north of the country, took over the capital in September last year, eventually driving Hadi south. The rebels then advanced over large swaths of the country, backed by army units loyal to Saleh, Hadi's predecessor. At their biggest advance, they nearly overwhelmed Aden, Yemen's second largest city and the refuge of pro-Hadi forces, at the far southern tip of the country. In March, Houthis seized government buildings inside Taiz and encircled the city.
But in recent months they have been pushed back on several fronts under the air campaign led by Saudi Arabia, backing a mix of anti-Houthi forces, including tribal fighters, southern separatists, Islamic militants, other militias and army units loyal to Hadi. They secured Aden in July and retook control of several southern provinces.
Progress to reach Taiz, 100 kilometers (62 miles) northwest of Aden, has been slow as they go through land mines planted by the Houthis, who have also been sending reinforcements from the north. Fighting has intensified as the two warring sides hold preliminary consultations in Oman this week to prepare for peace negotiations.
The punishment in Taiz has escalated, residents say, particularly after local fighters drove the Houthis out of most of their positons inside the city in August. About 1,643 civilians were killed in Taiz since March, most of them since September by Houthi shelling, said Abdul Rahim Alsamie, a doctor and activist in the humanitarian aid sector in Taiz.
"The humanitarian situation in Taiz is beyond catastrophic," Alsamie said.
In a mountainous area, Taiz is bottled up by Houthi forces, with land mines and snipers at the entrances to the city, he said. They prevent supplies from entering, except for smugglers who can sometimes get by either risking their lives through back roads or paying bribes to the rebels, he said.
Al-Mekhlafi, the engineer, said he sometimes walks several kilometers to reach a site with drinking water, and his home hasn't had electricity since March. He said Saudi planes drop weapons for the residents, but not food or other supplies.
Unemployed Taiz youth are taking up the weapons to fight the Houthis, he said.
"We are scared ... that our children will become militia fighters," said al-Meklhafi, who has two sons and a daughter between the ages of 8 and 15. "The general culture now is the culture of weapons, and that's what we fear for our children in the future."
Hayam al-Qadasi, general manager of Morooj Foundation for Human Development in Taiz, gave a similar figure of around 1,600 civilians killed. Her organization and others used donkeys and vehicles to transport good through unpaved roads in the mountains, but the Houthis found these routes and blocked them off, she said.
"Taiz is a peaceful city. Taiz is a city of culture, a city of civilization. Taiz doesn't deserve all this violence," she said.
Mazen reported from Cairo.