In a major escalation of Yemen’s civil conflict, rival factions in the southern city of Aden fought for control of the international airport and a security base, leaving at least three people dead, according to Yemeni officials.

Explosions could be heard throughout the city on Thursday, and at one point, warplanes conducted bombing raids on the compound of Yemen’s president, Abdu Rabbu Mansour Hadi, who was unharmed.

Violence has flared repeatedly in Yemen since the Zaydi Shiite rebel militia, known as the Houthis, took control of the capital, Sana, in September, setting off a power struggle between political factions and militias that has brought the country closer to civil war.

But outbreaks of large-scale fighting in the port city of Aden have been rare. The clashes on Thursday quickly raised fears of a widening conflagration in the south, a stronghold for a separatist movement as well as a powerful affiliate of Al Qaeda.

Tensions in the city had been building for some time, mirroring a broader political crisis that has essentially divided the country between rival seats of power in Sana and Aden.

As the Houthis have consolidated their control of northern Yemen, Mr. Hadi, who was all but forced from office by the Houthis and fled to Aden last month, has sought to re-establish his authority in the south.

Foreign powers have become more and more actively involved in the power struggle, with Iran backing the Houthis and Mr. Hadi drawing support from neighboring Persian Gulf nations fearful of Iranian influence, led by Saudi Arabia.

Armed men have been streaming into Aden for months. Mr. Hadi has been gathering his own force, composed of military units and tribesmen, intended to counter the strength of the Houthis and their allies — among them Yemen’s former president, Ali Abdullah Saleh, who still commands the loyalty of some security forces in southern Yemen.

Mr. Hadi, in an attempt to solidify his control of Aden, had tried unsuccessfully to dismiss the commander of the Special Security Forces, one of the units loyal to Mr. Saleh and feared in Aden for its crackdown on southern protesters.

The unit was said to have set off the fighting on Thursday by storming the airport, drawing a response from Mr. Hadi’s loyalists.

Hours of intense fighting with heavy weapons forced passengers on a plane preparing to depart to Cairo to disembark, and damaged one of Mr. Hadi’s presidential planes, according to an Associated Press reporter who was at the scene.

After receiving military reinforcements, Mr. Hadi’s forces were able to regain control of the airport, and later overran the Special Security Forces base, according to a senior government official.

As residents celebrated the storming of the base, air force jets, apparently acting on orders of either the Houthis or Mr. Saleh, bombed Mr. Hadi’s compound in Aden, striking a building there, the official said.

As the fighting subsided, the Houthis released a statement from Sana, calling for dialogue and a restoration of calm. The fighting appeared, at least momentarily, to strengthen the hand of Mr. Hadi, once considered a weak, caretaker president who has enjoyed an unlikely resurgence after fleeing house arrest by the Houthis.

Beyond simply surviving the day’s fighting, Mr. Hadi could count on greater support in Aden, including from supporters of the southern separatist movement, for taking on the Special Security Forces, according to Yasser al-Yafae, the editor of a local news website.

“They murdered many leading activists,” he said of the security unit.

It remained to be seen how Mr. Saleh would respond, after the humiliating defeat of his loyalists in Aden at the hands of Mr. Hadi, his main adversary. Mr. Saleh, who was removed from power in 2012 as part of a deal brokered by the Persian Gulf nations, has remained one of Yemen’s most influential political figures, and a frequently disruptive force.

NY Times