The Taliban seized the city of Kunduz in northern Afghanistan on Sunday, officials said. It is the first major city to be overtaken by the insurgents since they began their sweeping military offensive in May, and it happened just weeks before U.S. forces were set to complete a total withdrawal from Afghanistan.

It was also the third provincial capital to be overtaken by Taliban in three days, and a major blow to the Afghan government.

Kunduz, the capital of a province of the same name, is a significant military and political prize. With a population of 374,000, it is a vital commercial city near the border with Tajikistan, and a hub for trade and road traffic.