The Taliban has launched a coordinated assault on the city of Kunduz in Afghanistan, attacking from four directions and entering deep into the city.
Sheer Ali Kamal, commander of the 808 Tandar police zone in Kunduz, said on Monday the attack began at midnight (1930GMT on Sunday) and fighting was still ongoing in and around the city.
"We are putting all our efforts together to push them back," he said.
Military helicopters were flying overhead and gunfire could be heard within the city.
Taliban fighters took control of the central intersection in Kunduz where they raised their flag a year ago in their biggest success of the 15-year-old conflict.
Witnesses and police said they was attacking the governor's compound and police headquarters, while some officials were seen fleeing to the airport.
With fighting also intensifying in the strategic southern province of Helmand, the attack on Kunduz - a day before a major international donors' conference in Brussels - underlined Afghanistan's precarious security situation and the Taliban's ability to strike important targets.
"It will be difficult to dislodge them as we understand that the Taliban have taken positions inside civilian homes. Police and security forces are having difficulty distinguishing where exactly the fire is coming from," said Al Jazeera's Jennifer Glasse, reporting from the capital Kabul.
|Al Jazeera's Hashmat Moslih puts the attack in context|
Kunduz, which fell briefly to the Taliban a year ago, has seen repeated bouts of heavy fighting.
A Taliban spokesman, Zabihullah Mujahid, earlier announced the attack on Twitter.
He said the Nawabad area, and four checkpoints there, had been captured and several soldiers had been killed in a statement that was not immediately possible to verify.
A Reuters news agency journalist saw at least five Taliban fighters armed with AK-47 assault rifles, machine guns and rocket-propelled grenades in the city.
Brigadier General Charles Cleveland, spokesman for the NATO-led Resolute Support mission in Kabul, said the situation in Kunduz was "fluid" and US forces were ready to assist.
'A show of force'
Amnesty International called on all parties to take "all feasible precautions to protect civilians, including media and humanitarian workers".
"Needlessly endangering civilians by launching attacks from their midst is prohibited under international law, and demostrates the Taliban's utter disregard for civilian safety and right to life," it said in a statement.
The attack came as the Taliban stepped up operations in different parts of Afghanistan, including southern Helmand, where they have been threatening the provincial capital of Lashkar Gah.
Glasse said they also attacked Nawa district in Helmand province, killing its police chief. "This does seem like a show of force by the Taliban."
The fall of Kunduz last year was one of the most serious blows suffered by the Western-backed government in Kabul since the withdrawal of most foreign troops at the end of 2014.
A Taliban raid on Tarin Kot, the provincial capital of Uruzgan in the south, on September 8 also sparked fears of another collapse.
Government forces are estimated to have control over no more than two-thirds of the country.
At the Belgium conference, Afghanistan's foreign donors are expected to approve maintaining billions of dollars in funding for the government over the next four years.
Al Jazeera analyst Hashmat Moslih said both the government and the Taliban had gained something from Monday's attack.
"The Taliban are going to show their force, the government is going to claim that they need more funding," he said.
He added the country's leaders were divided along the ethnic lines and there were certain elements in the government who did not want to take on the Taliban.
"They use the Taliban as a bargaining chip against their political foes inside the government."
|Afghan security forces retook control of Aachin district of Kunduz after it was briefly taken over by the Taliban in August [EPA]|
Source: Al Jazeera News And Agencies