ADEN, Yemen — Street battles raged on Sunday in residential areas of Yemen's main port city of Hodeida, forcing some medical staff to flee the largest hospital, as Iranian-aligned Houthi insurgents tried to repel forces backed by a Saudi-led coalition.

The city on the Red Sea is an entry point for most of the country's food and relief supplies. The United Nations and aid groups have warned that a full-scale assault on Hodeida could trigger a famine in the already impoverished Arabian Peninsula state, which imports 90 percent of its food, according to the U.N.

Pro-government forces advance towards central Hodeida on Thursday. Khaled Ziad / AFP - Getty Images

Residents said they saw bodies of seven civilians killed in clashes in southern suburbs, with both sides using mortar shells, anti-aircraft guns and assault rifles in the fight. Fighting, which first started to intensify in June, has not yet reached the center of the city, according to Sarah Alzawqari, a spokesperson for the International Committee of the Red Cross.

The coalition has renewed its offensive on Hodeida as Western allies, including the United States, called for a ceasefire to support U.N.-led efforts to end the nearly four-year war that has killed more than 10,000 and pushed the country to the brink of starvation. The Houthis control of much of the country, including the capital, Sanaa.

Medical sources at al-Thawra hospital told Reuters that several staff members and patients able to move had fled the complex. It was not immediately clear how many patients remained inside. There are around 25 to 30 people who can't be moved who are in the hospital's intensive care unit, according to the ICRC.

"The Houthis are reinforcing their positions near the hospital and that is what scared people," said one staff member.

Hospital spokesman Khaled Attiyah told Reuters that doctors and nurses continued their work in departments such as intensive care, the burns ward and the emergency room "despite the panic."

“The hospital is still able to get food and supplies that are needed, but if one party enters it or uses it for military purposes it will be a huge problem and dangerous for the people there,” said Alzawqari.

Last week, rights groups said the Houthis had raided the May 22 hospital in the city's eastern suburbs and posted gunmen on the roof, endangering doctors and patients.

More than two dozen senior Obama administration officials, including former National Security Advisor Susan Rice and former CIA Director John Brennan, called on President Donald Trump on Sunday to cease all support for the war.

In a telephone call with Saudi Crown Prince Mohammed bin Salman on Sunday, Secretary of State Mike Pompeo reiterated Washington's call for "a cessation of hostilities and for all parties to come to the table to negotiate a peaceful solution to the conflict," the State Department said.

The U.N. humanitarian chief said last month that "there is a clear and present danger of an imminent and great big famine engulfing Yemen."

The World Food Program said its cargo vessels were still able to call at the port in Hodeida, but it didn’t have access to some silos where grain is stored. Pro-coalition forces took control on Saturday of Red Sea Mills, a main grains facility south of the port which holds about 51,000 tons of wheat, a U.N. aid group said.

"Around 60 shells fell inside the compound since the clashes reached that area few days ago but the silos and the grains were not touched," said Ali Reza Qureshi, Yemen's deputy director for the WFP.

"We hope the production will resume in the coming next two weeks as we get 21,000 tons monthly from those mills, otherwise we will have to import wheat flour," he told Reuters.

The WFP said last week it plans to double its food assistance program for Yemen, aiming to reach up to 14 million people "to avert mass starvation."

Yemeni pro-government forces gather on the eastern outskirts of Hodeida on Saturday. AFP - Getty Images

The coalition has said that wresting control of Hodeida would break the Houthis by cutting off their main supply line and force the group to the negotiating table to end the conflict, seen as a proxy war between Riyadh and Iran.

The alliance, which relies on the West for arms and intelligence, intervened in Yemen's war in 2015 to restore the internationally recognized government ousted by the Houthi movement, which controls the most populated areas of Yemen including the capital Sanaa.

U.N. special envoy Martin Griffiths has said he hopes to convene renewed peace talks by the end of the year after the last round of consultations collapsed in September.

The United Nations has no up-to-date estimate of the death toll in Yemen. It said in August 2016 that according to medical centers at least 10,000 people had been killed.