SANAA, Yemen (AP) — Yemeni President Abed Rabbo Mansour Hadi fled the country by sea Wednesday on a boat from Aden, as Shiite rebels and their allies advanced on the southern port city where he had taken refuge, captured his defence minister and seized the city’s airport.

Hadi’s departure marks a dramatic turn in Yemen’s turmoil and means a decisive collapse of what was left of his rule, which the United States and Gulf allies had hoped could stabilize the chronically chaotic nation and fight al-Qaida’s branch here after the 2011 ouster of longtime autocrat Ali Abdullah Saleh.

Over the past year, the Shiite rebels known as Houthis, who are believed to be supported by Iran, have battled their way out of their northern strongholds, overwhelmed the capital, Sanaa, seized province after province in the north and worked their way south. Their advance has been boosted by units of the military and security forces that remained loyal to Saleh, who allied with the rebels.

With Hadi gone, there remains resistance to the Houthis scattered around the country, whether from Sunni tribesmen, local militias, pro-Hadi military units or al-Qaida fighters.

Hadi and his aides left Aden after 3:30 p.m. on two boats, security and port officials told The Associated Press. The officials would not specify his destination. But Hadi is scheduled to attend an Arab summit in Egypt on the weekend, where Arab allies are scheduled to discuss formation of a joint Arab force that could pave the way for military intervention against Houthis.

His flight came after Houthis and Saleh loyalists advanced against Hadi’s allies on multiple fronts. Military officials said militias and military units loyal to Hadi had “fragmented,” speeding the rebel advance. The officials spoke on condition of anonymity because they were not authorized to speak to reporters

Earlier in the day, the rebels seized a key air base where U.S. troops and Europeans had advised the country in its fight against al-Qaida militants. The base is only 60 kilometres (35 miles) away from Aden.

In the province of Lahj, adjoining Aden, the rebels captured Hadi’s defense minister, Maj. Gen. Mahmoud al-Subaihi, and his top aide on Wednesday and subsequently transferred them to the capital, Sanaa. Yemen’s state TV, controlled by the Houthis, announced a bounty of nearly $100,000 for Hadi’s capture.

Hadi then fled his presidential palace, and soon after warplanes targeted presidential forces guarding it. No casualties were reported. By midday, Aden’s airport fell into hands of Saleh’s forces after intense clashes with pro-Hadi militias.

Aden was tense Wednesday, with schools, government offices, shops and restaurants largely closed. Inside the few remaining opened cafes, men watched the news on television. With the fall of the city appearing imminent, looters went through two abandoned army camps, one in Aden and the other nearby, taking weapons and ammunition.

The takeover of Aden, the country’s economic hub, would mark the collapse of what is left of Hadi’s grip on power. After the Houthis overran Sanaa in September, he had remained in office, but then was put under house arrest. He fled the capital earlier in March with remnants of his government and declared Aden his temporary capital.