Saudi-backed forces on Saturday captured Hadramaut's desert and valley region and advanced toward the coastal areas, as airstrikes hit the STC forces headquarters in Mukalla amid deepening confrontations between Riyadh- and Abu Dhabi-backed factions.
The Yemeni government announced that its National Shield Forces have gained full control of the desert and valley region in eastern Hadramaut province and are now moving toward the coastal districts.
Plumes of smoke were seen rising from the Parshid Brigade headquarters, west of Mukalla, the provincial capital of Hadramaut, witnesses told state-run Anadolu Agency (AA). No details were yet available about casualties or the party behind the strikes.
In a statement, the military of the Saudi-aligned government announced that "all military and civilian facilities" in Mukalla had "been secured" by Riyadh-backed forces.
Hadramaut Governor Salem al-Khanbashi declared the successful completion of operations to capture military camps in the desert and valley region.
He said National Shield Forces completed their deployment at all vital sites, fully securing Seiyun International Airport as well as sovereign and service facilities across the Hadramaut desert and valley region.
Two government military officials told Agence France-Presse (AFP) they had taken control of Mukalla's principal military base.
In Seiyun, 160 kilometers (100 miles) northwest of Mukalla, a government military official said pro-Saudi forces had taken control of the airport, targeted in Friday's strikes, as well as administrative buildings.
"We are working to secure them," the military official said.
Tribal forces loyal to the Yemeni government said they have captured the presidential palace in the city of Seiyun.
The Hadramaut Protection Forces, affiliated with the Hadramaut Tribes Alliance, said in a video statement that they have "secured the presidential palace in Seiyun to protect it from any looting."
The forces said they have informed the security administration that the palace remains under their protection "until National Shield Forces arrive to take it over."
The presidential palace is considered one of the most important sovereign sites in Hadramaut and carries strong symbolic significance.
The Hadramaut Protection Forces also said they had captured several military sites from the STC in Mukalla, urging residents "to stay away from any other locations where STC fighters are present and to halt looting and theft."
The STC military official said, "There has been a retreat of our forces and we are resisting the attacking forces in Seiyun."
"We carried out a complete withdrawal from the areas of Al-Khasha as a result of pressure from Saudi air strikes on us," he added.
According to an AFP journalist, gunfire could be heard in Mukalla early Saturday. While residents described a security breakdown accompanied by looting, Saudi-backed forces appeared to advance with little resistance.
Hani Yousef, a Mukalla resident, said he "saw retreating forces using their military vehicles to transport motorbikes and household items, including refrigerators and washing machines."
Residents in Seiyun also said they heard gunfire and clashes.
The Saudi-led coalition has launched repeated warnings and airstrikes over the past week, including one on an alleged Emirati arms shipment to the STC.
On Friday, a strike on the Al-Khasha military camp in Hadramaut left 20 dead, according to the separatist group.
On Saturday, a military official with the STC told Agence France-Presse (AFP) Saudi warplanes had carried out "intense" airstrikes on the group's camp at Barshid, west of Mukalla. The official said the strike had resulted in fatalities without giving a number.
Footage aired by the Aden Independent Channel showed the moment one strike hit the STC forces, igniting a massive orange fireball and sending a plume of black smoke into the sky.
The Saudis and Emiratis have for years supported rival factions in Yemen's fractious government. But a recent offensive by the UAE-backed STC to capture Hadramaut angered Riyadh and left the oil-rich regional powers on a collision course.
Saudi Arabia accused the UAE of "pushing STC forces to carry out military operations" along the kingdom's southern border in Hadramaut and Al-Mahra. Abu Dhabi denied the accusation.
Hadramaut is Yemen's largest governorate by area, accounting for roughly one-third of the country's total territory. It is administratively divided into two parts: coastal districts with Mukalla as the largest city and valley and desert districts with Seiyun as the largest city.