A Saudi-led coalition geared up on Tuesday for an assault on Yemen's main port, preparing to launch by far the biggest battle of a three-year-old war between an alliance of Arab states and the Houthi movement that controls Yemen's capital.
Emirati forces with Yemeni government troops moved in from the south near Hodeida's airport, while others sought to cut off Houthi supply lines to the east, the officials said.
Saudi Arabia, the United Arab Emirates and a bloc of other countries intervened the following year with the goal of restoring the government to power.
The bombing began on Wednesday after the rebels ignored a deadline set by the Yemeni government to withdraw from the port.
The Saudi-led coalition accuses the Huthis of using the port to secure Iranian arms, notably the ballistic missiles the militants have increasingly fired into Saudi territory.
According to medical sources in the province, 22 Huthi fighters have been killed over the past 24 hours by coalition raids, while three pro-government fighters were killed in a rebel ambush south of Hodeida.
UN Secretary-General Antonio Guterres told Yemen's Foreign Minister Khaled Alyemany on Monday that every effort must be made to "avoid a fierce, bloody battle for Hodeida", a UN spokesman said.
"I am extremely concerned about military escalation in #Hodeida & their humanitarian & political impact", he said in a tweet.
Four Emirati soldiers were killed in Wednesday's assault, the United Arab Emirates' state-run news agency said, but gave no details of how they died.
Hodeida is some 150 kilometers (90 miles) southwest of Sanaa, Yemen's capital, which has been in Houthi hands since September 2014. The Saudi-led coalition entered the war in March 2015.
United Nations spokesman Stephane Dujarric told reporters at United Nations headquarters in NY on Wednesday that aid partners are delivering 70,000 rapid response kits to "humanitarian service points" in and around Hodeida for newly displaced families.
Saudi-owned satellite news channels have announced the start of the Saudi-led coalition's assault on Hodeida.
"We are not giving up", a Security Council diplomat said.
Some 2,000 troops who crossed the Red Sea from an Emirati naval base in the African nation of Eritrea were awaiting orders to move in from the west after Yemeni government forces seize Hodeida's port, Yemeni security officials said.
The UN on Monday withdrew all of its global staff from Hodeida ahead of the impending assault, warning that any offensive would put millions of lives at risk. The sound of heavy, sustained gunfire clearly could be heard.
The U.N. says some 600,000 people live in and around Hodeida, and "as many as 250,000 people may lose everything- even their lives" in the assault. Military sources said the deaths were caused by mines and snipers.