Sunni tribal fighters and Iraqi police carry their weapons as they stand guard against attacks from ISIS militants, in Ramadi.

Islamic State of Iraq and Syria (ISIS) militants withdrew from the main government building in the Iraqi city of Ramadi on Saturday, the mayor and a tribal leader said, a day after the jihadist group raised its black flag over the building in the western provincial capital.

Airstrikes by a U.S.-led coalition forced the militants to retreat, leaving the buildings booby trapped or on fire, the officials said. Their reports could not be confirmed independently.

Al Arabiya News Channel’s correspondent reported Saturday that the airstrikes have killed at least 30 ISIS militants west of the Iraqi province of Anbar.

The news comes after Iraq’s military dispatched reinforcements to help its battered forces in Ramadi, an Iraqi military spokesman said Saturday.

The spokesman of the Joint Operations Command, Brig. Gen. Saad Maan Ibrahim, told Iraqi state television that the U.S.-led coalition was supporting Iraqi troops with “painful” airstrikes since late Friday.

Ibrahim didn’t give details on the ongoing battles, but described the situation on the ground as “positive” and vowed that ISIS would be pushed out of the city “in the coming hours.”

On Friday, the militants swept through Ramadi, the capital of Anbar province, launching a coordinated offensive included three near-simultaneous suicide car bombs. The militants seized the main government headquarters and other key parts of the city.

Local officials said dozens of security forces and civilians were killed, mainly the families of the troops, including 10 police officers and some 30 tribal fighters allied with Iraqi forces.

In a sign of how the latest advance is worrying Washington, U.S. Vice President Joe Biden spoke with Iraqi Prime Minister Haider Al-Abadi on Friday, promising the delivery of heavy weapons, including AT-4 shoulder-held rockets to counter suicide car bombs, according to a U.S. Embassy statement.

The statement said both leaders agreed on the “importance and urgency of mobilizing tribal fighters working in coordination with Iraqi security forces to counter ISIL and to ensure unity of effort among all of Iraq’s communities,” using a different acronym for the group.

Meanwhile, U.S. officials are pressing that ISIS is on the defensive in Iraq, despite the extremist group’s gains in Ramadi and an intense fight to keep the oil refinery in Baiji from falling to the terrorist group’s control.

“It is a tough fight right now,” said Operation Inherent Resolve commander Brig. Gen. Thomas Weidley.

In Ramadi, “Daesh executed a complex attack on Iraqi security forces [Friday,]” Weidley said, using the Arabic derogatory term for ISIS. The Iraqi forces were able to repel most of the attacks, but “some gains were made by Daesh” in the east and south of the city.

Backed by U.S.-led airstrikes, Iraqi forces and Kurdish fighters have made gains against ISIS, including capturing the northern city of Tikrit. But progress has been slow in Anbar, a vast Sunni province where anger at the Shiite-led government runs deep and where U.S. forces struggled for years to beat back a potent insurgency. American soldiers fought some of their bloodiest battles since Vietnam on the streets of Fallujah and Ramadi.

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