SANAA, Yemen — Troops from a U.S.-backed, Saudi-led coalition pounded Houthi rebel positions in Yemen's port city of Hodeida with airstrikes and a ground assault on Wednesday. They now control a major road leading into the city, military officials and witnesses on both sides of the front line said.

Hodeida has become the epicenter of Yemen's conflict. Its port is a lifeline for millions of Yemenis who are at risk of famine, BBC News reports. As much as 80 percent the humanitarian supplies, fuel and commercial goods that they depend on are delivered through the facility. Officials with the United Nations have warned that if it is damaged, destroyed or blocked, the toll in lives could be catastrophic.

The Saudi-led coalition, which seeks to restore to power the internationally recognized Yemeni government, has been at war with the Houthis since March 2015. The U.S. has sold billions of dollars' worth of arms to Saudi Arabia and provides logistical and other support to the coalition.

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A renewed coalition offensive on Hodeida began five days ago. Dozens of fighters have been killed and hundreds wounded from both sides since the renewed offensive started. The fighting has left dead bodies lying on the ground and inside burnt-out vehicles at the city's edge, according to witnesses. They said several civilians have been killed by shelling in residential areas.

A Save the Children-supported health facility in Hodeida came under attack on Tuesday morning, damaging one of the pharmacies that supply life-saving medicines, the charity said in a statement. The group said shelling has also hit residential areas in Hodeida, where the lives of hundreds of thousands of people, roughly half of them children, are in danger.

The head of the U.N.'s food and agriculture agency and other groups say the conflict has pushed Yemen to the brink of famine, underlining how the international community is failing to end hunger.

"We are watching before our eyes an unprecedented human tragedy," Food and Agriculture Organization chief Jose Graziano da Silva told a high-level briefing on food insecurity at the U.N. in New York.

"Yemen is living proof of an apocalyptical equation: conflicts and food security go hand in hand, and when there is an overlap of climate change and conflict, famine is already on the horizon," he said.