The Taliban have captured three regional capitals in Afghanistan as they continue to make sweeping territorial gains in the country.
They seized control of the key northern city of Kunduz on Sunday, as well as Sar-e-Pul and Taloqan.
It means five regional capitals have fallen to the militants since Friday, with Kunduz being their most important gain this year.
The city is well connected to other areas, including the capital Kabul.
Violence has escalated across Afghanistan after US and other international forces began to withdraw their troops from the country, following 20 years of military operations.
Taliban militants have made rapid advances in recent weeks. Having captured large swathes of the countryside, they are now targeting key towns and cities.
The three northern cities fell to Taliban control within hours of each other on Sunday, with one resident in Kunduz describing the situation as “total chaos”.
The Afghan government, meanwhile, said its forces were fighting to retake key installations.
Heavy fighting has also been reported in Herat in the west, and in the southern cities of Kandahar and Lashkar Gah.
Thousands of civilians have been displaced this year. Families, including babies and young children, have been sheltering in a school in the north-eastern city of Asadabad.
“Many bombs were dropped on our village. The Taliban came and destroyed everything. We were helpless and had to leave our houses. Our children and ourselves are sleeping on the ground in dire conditions”, Gul Naaz told AFP.
“There was firing, one of my seven-year-old daughters went out during that fighting and disappeared. I don’t know if she is alive or dead,” another displaced resident said.
The US has intensified its air strikes on Taliban positions, with Afghan military officials saying militants have been killed. But the Taliban say the air strikes hit two hospitals and a school in the city of Lashkar Gah. Neither claim has been independently verified.
The US embassy in Afghanistan condemned the Taliban’s “violent new offensive against Afghan cities”, saying the group’s actions to “forcibly impose its rule are unacceptable”.
“They demonstrate wanton disregard for the welfare and rights of civilians and will worsen this country’s humanitarian crisis,” it said in a statement.
A big change on the battlefield
By Khalil Noori, BBC News, Kabul
This attack on a number of strategic cities and their fall to the Taliban was unprecedented. But as the deadline for the full withdrawal of foreign forces approached, a big change on the battlefield was expected.
Now it is time for the Afghan government to prove that its well-equipped forces, 350,000 strong, are able to retake the lost areas.
It would be difficult for the Taliban to hold Kunduz, but for several weeks the group has kept control of commercial centres important for trade with Iran and Pakistan.
The populations in cities taken by the Taliban are paying the price of war, having lost loved ones or property. They are having to leave their homes, fearing the launch of a government operation to retake the cities.
Peace talks with the Taliban in Doha are deadlocked. If the process resumes, from now on both sides will be trying to control the larger area to justify a greater share of power, if they agree on a transitional government.