Gunmen stormed a Kabul guesthouse popular with foreigners late on Wednesday ahead of a planned concert, Afghan officials said, with people believed trapped inside and several casualties feared.
No group immediately claimed responsibility for the attack on the Park Place guesthouse in downtown Kabul, but the assault comes as the Taliban - who have attacked such guesthouses in the past - press their annual spring offensive.
"There was a concert planned to take place inside the Park Place tonight, with foreigners, mainly Indian and Turkish guests, invited," an Afghan intelligence official told AFP on condition of anonymity.
"The attack started before the concert. We believe three to five gunmen have managed to sneak into the guesthouse, but they first faced resistance from the guards."
A Park Palace employee, who barricaded himself in a room in the guesthouse, told AFP he heard several people screaming in the corridors as gunshots rang out.
"A party with live Afghan music was playing upstairs - with several VIPs attending - when the gunfire started," he told AFP by telephone.
The employee, who did not wish to be named, later managed to flee the guesthouse and said he saw at least five blood-covered bodies lying near the entrance.
Roads leading up to the guesthouse were blocked by a large number of security personnel who arrived after the attack, according to an AFP photographer at the scene.
Kabul police chief Abdul Rahman Rahimi, who was at the scene of the ongoing attack, said security forces were trying to get inside the guesthouse, but were facing heavy gun fire from the assailants.
The Taliban has been behind previous attacks on compounds and guesthouses occupied or frequented by foreigners, including at least two separate assaults in Kabul in November.
Militants also launched a major attack on a compound of the International Organization for Migration in 2013.
Along with guesthouses and compounds, the range of targets hit last year in Kabul included the Afghan capital's most prestigious hotel and a restaurant popular with Western diplomats.
Taliban insurgents, who have waged a 13-year war to topple the US-backed Afghan government, launched their spring offensive across Afghanistan late last month, stepping up attacks on government and foreign targets.
This year marks the first fighting season in which Afghan forces are battling the insurgents without the full support of US-led foreign combat troops.
Nato's combat mission formally ended in December but a small follow-up force has stayed on to train and support local security personnel.
Pakistan prime minister Nawaz Sharif on Tuesday assured Kabul of full support in its battle against the Taliban, saying "the enemies of Afghanistan cannot be the friends of Pakistan".
His comments are the latest sign of a thaw in the once-frosty relationship between the two countries.
Afghan officials have frequently accused longtime nemesis Pakistan of harbouring and nurturing Taliban insurgents.
But Afghan President Ashraf Ghani has actively courted Pakistan since coming to power in what observers say is a calculated gambit to pressure the insurgents to the negotiating table.