Hundreds of Taliban fighters have carried out an early-morning raid on the city of Kunduz in Afghanistan, entering the northern city from three different directions, sources tell Al Jazeera.
At least eight people, including police officers, have been killed, and 50 others wounded.
Al Jazeera's Abdullah Shahood, reporting from the capital Kabul, said Kunduz City was in lockdown on Monday as security forces attempted to fight back.
He said heavy fighting continues across the city, roads had been blocked and some police stations within the city were surrounded by Taliban fighters.
There have been reports that the provincial council building has been seized.
Mohammad Yusouf Ayubi, the head of the Kunduz provincial council, told AP news agency that city residents were "greatly concerned" about the situation.
"The Taliban are trying to take control of Kunduz City and this is why they have launched their attacks from different directions using their full power," he said.
The armed fighters have also reportedly taken control of a 200-bed hospital in the city following the raid on Monday, a Taliban spokesman and a police source told Reuters.
Moein Marastial, a former parliament member from Kunduz, told Al Jazeera that a university in Kunduz has also been taken over by the Taliban.
He said the Taliban has gained the support of Kunduz residents, who were unhappy about local government corruption.
The city's streets were deserted as residents barricaded themselves indoors.
Opinion: Afghan government is sleeping with the enemy
"The situation is very bad. The fighting is particularly fierce in the southeastern area of the city," a Western NGO official told AFP news agency on condition of anonymity.
According to Al Jazeera sources, Taliban fighters are reportedly searching houses in the city looking for government officials.
The fighters have also reportedly blocked roads leading to the airport and the hospital to prevent civilians from fleeing the city, and government reinforcements from entering it.
Additional government troops have been deployed to the area, but they have not reached the city, the government told Al Jazeera.
The attack is the second time this year that the Taliban threatened to seize Kunduz, which is the main city of Kunduz province.
The province is one the most volatile provinces in the northern region of the country, with three districts reportedly under Taliban control.
|Afghan soldiers keep watch during a battle with the Taliban in Kunduz Province on Monday [Reuters]
The Taliban have been waging an armed struggle since a US-led invasion ousted them from power in late 2001, and have stepped up attacks during a summer offensive launched in late April against the Western-backed government in Kabul.
On Sunday, 13 people were killed and 33 wounded at a volleyball match in the eastern province of Paktika, while a splinter group affiliated with the Islamic State of Iraq and the Levant (ISIL) launched coordinated attacks on police checkpoints in the eastern province of Nangarhar.
Afghanistan's NATO-trained police and army have been fighting armed rebels this year without the front-line help of foreign forces, which ended their combat mission in December 2014.
A residual force of around 13,000 remains for training and counterterrorism operations.
Peace overtures by the government of President Ashraf Ghani over summer ended in failure, as civilian casualties soared to a record high in the first half of 2015 according to a UN report.
It said 1,592 civilians were killed, a six percent fall over last year, while the number of injured jumped four percent to 3,329.
Source: Al Jazeera and agencies