Militia men loyal to Yemeni President Abed Rabbo Mansour Hadi looted a military barracks in the southern port city of Aden on March 19, 2015. (Yaser Hasan/Reuters)

— Intense clashes erupted Thursday in southern Yemen between forces loyal to the beleaguered president and the Shiite rebels whose assaults have pushed the Arabian Peninsula country into chaos.

Airstrikes targeted the palace of Abed Rabbo Mansour Hadi in the southern port city of Aden, to which he fled last month after escaping captivity by the rebels, known as Houthis. The rebels now control the capital, Sanaa.

The air raids followed a siege earlier in the day at the airport in Aden, where Hadi has set up a rival governing authority. The split raises the specter of an all-out civil war and could drag Yemen into a proxy conflict between the region’s two most powerful countries: Sunni Saudi Arabia and Shiite Iran. Hadi’s authority in the south is backed by Riyadh, while the Houthis, who are followers of the Zaydi sect of Shiite Islam, have received increasing support from Tehran.

[Read: Who are the Houthis?]

Hadi’s allies blamed Thursday’s airstrikes on the Houthis, who seized warplanes and other military equipment during their march on Sanaa in September and in battles elsewhere against tribal forces and the country’s powerful al-Qaeda affiliate. Hadi was unharmed in the air raids, officials close to him told local media. They also said the palace was not damaged.

“The two airstrikes by the Houthis are a form of extremism and an act of aggression,” the governor of Aden province, Abdul-Aziz bin Habtoor, said in a televised address.

The air raids followed clashes earlier in the day at Aden’s airport that killed at least six people, according to Yemeni media reports. The fighting at the airport pitted Hadi’s forces against military units in the south that have remained loyal to Ali Abdullah Saleh, an autocrat who was ousted as president by an uprising that began in 2011.

[Read: A key player in Yemen’s political chaos? A strongman ousted in 2012.]

Mortar rounds were fired at the airport, local media reported. Pro-Hadi forces reportedly repelled the assault, with reinforcements arriving from Hadi’s defense minister, Mahmoud al-Subaihi.

Citing an unidentified official, the Associated Press reported that the fighting damaged one of Hadi’s presidential planes, a Boeing 747. The AP also reported that 100 passengers on a Cairo-bound flight were forced to deplane and rush inside the terminal because of the clashes.

After the airport fighting, pro-Hadi forces captured a military base that housed a unit loyal to Saleh.

Earlier this month, Subaihi fled to Aden from Sanaa, where the Houthis had placed him under house arrest after toppling the Hadi-led government. The Houthis also placed Hadi under house arrest and compelled him to resign. After escaping to Aden, Hadi rescinded his resignation, saying he was the country’s legitimate president.

The involvement of pro-Saleh forces in the fighting adds to widespread suspicion in Yemen that the former leader has conspired against Hadi by aiding the Houthi advances. In November, the U.N. Security Council imposed sanctions on Saleh for allegedly undermining stability in Yemen.

In a sign of support for Hadi, Saudi Arabia, the United Arab Emirates and Bahrain have dispatched ambassadors to Aden after dismantling their embassies in Sanaa last month.

Iran has offered to supply the Houthi-controlled government with gas, build it a power plant and finalize a deal for 14 direct flights between the two countries every week.