The Taliban seized a province just south of Afghanistan’s capital and launched a multi-pronged assault early Saturday on a major city in the north defended by powerful former warlords, Afghan officials said.

Taliban militants have captured Warsaj district, the last bastion of the Afghan government in Takhar province, and further consolidated their position in the country’s northern region, an official said on Saturday.

The insurgents have captured much of northern, western, and southern Afghanistan in a breakneck offensive less than three weeks before the United States is set to withdraw its last troops, raising fears of a full militant takeover or another Afghan civil war.

The Taliban captured all of Logar and detained its provincial officials, Hoda Ahmadi, a lawmaker from the province, said Saturday. She said the Taliban have reached the Char Asyab district, just 11 kilometers (7 miles) south of the capital, Kabul.

The Taliban also attacked the northern city of Mazar-e-Sharif from several directions, setting off heavy fighting on its outskirts, according to Munir Ahmad Farhad, a spokesman for the provincial governor. There was no immediate word on casualties.

Afghan President Ashraf Ghani was delivering a televised speech on Saturday, his first public appearance since the recent Taliban gains. The president had flown to Mazar-e-Sharif on Wednesday to rally the city’s defenses, meeting with several militia commanders.

They remain allied with the government, but during previous rounds of fighting in Afghanistan, warlords have been known to switch sides for their own survival. Ismail Khan, a powerful former warlord who had tried to defend Herat, was captured by the Taliban when the insurgents seized the western city after two weeks of heavy fighting.

Residents of Mazar-e-Sharif expressed fear about the security breakdown.

“The situation is dangerous outside of the city and inside the city,” Mohibullah Khan said, adding that many residents are also struggling economically. “The security situation in the city is getting worse,” said Kawa Basharat. “I want peace and stability. The fighting should be stopped.”

The Taliban have made major advances in recent days, including capturing Herat and Kandahar, the country’s second-and third-largest cities. They now control 18 of Afghanistan’s 34 provinces, leaving the Western-backed government in control of a smattering of provinces in the center and east, as well as Kabul and Mazar-e-Sharif.

The withdrawal of foreign forces and the swift retreat of Afghanistan’s own troops — despite hundreds of billions of dollars in U.S. aid over the years — has raised fears the Taliban could return to power or the country could be shattered by factional fighting, as it was after the Soviet withdrawal in 1989.

The first Marines from a contingent of 3,000 arrived on Friday to help partially evacuate the U.S. Embassy. The rest are set to arrive by Sunday, and their deployment has raised questions about whether the administration will meet its Aug. 31 withdrawal deadline.

The Taliban meanwhile released a video announcing the takeover of the main radio station in the southern city of Kandahar, renaming it the Voice of Sharia, or Islamic law.