(TIME): Taliban fighters seized most of the capital of northern Afghanistan’s key Kunduz province on Sunday, and took another neighboring provincial capital after a monthlong siege. The advances were the latest in a series of blows to government forces as U.S. troops complete their pullout after nearly two decades in the country. The militiamen planted their flag in the main square of Kunduz city, where it was seen flying atop a traffic police booth, a video obtained by the Associated Press showed. It was the fourth provincial capital to largely succumb to Taliban fighters in less than a week, as they ramp up a push across Afghanistan’s regions, and wage an assassination campaign in the capital, Kabul. Two provincial council members said the Taliban took control of the governor’s office and police headquarters after a day of firefights, as well as the main prison building, where 500 inmates including Taliban fighters were freed. Kunduz’s capture would be a significant gain for the Taliban and a test of their ability to take and retain territory in their campaign against the Western-backed government. It is one of the country’s larger cities with a population of more than 340,000, and was a key area defended against Taliban takeover by Western troops over the years. Councilman Ghulam Rabani Rabani said that fighting was continuing at the city’s airport and other parts of the city still in government hands. Kunduz is a strategic crossroads with good access to much of northern Afghanistan as well as Kabul, about 200 miles (335 kilometers) away. Another provincial council member from Kunduz, Mohammad Yusouf Ayubi, also said Afghan forces only control the airport and main army barracks, and that the Taliban control the rest of the city. “The innocent and poor must pay the cost of the war in Kunduz and other parts of the country, both government forces and the Taliban are the enemy of civilians,” said Ayubi. “One can’t provide security and the other doesn’t care about people’s safety,” he added. The Afghan government in Kabul denies it has lost the northern city, which would be the fourth provincial capital to be largely overrun by Taliban fighters in the last week. Interior Ministry Spokesman Mirwais Stanekzai said that Afghan security forces continue to fight and have already retaken some areas from the Taliban, without elaborating. The Taliban has long considered the city a sought-after prize. It seized Kunduz, at the heart of a major agricultural region near Tajikistan, for around two weeks in 2015 before withdrawing in the face of a NATO-backed Afghan offensive. The insurgents pushed back into the city center a year later, briefly raising their flag before gradually being driven out again.