Six foreign UN employees have been killed and nine wounded in an attack in Kabul, the deadliest on the UN in Afghanistan since the Taliban's fall.
Three militants attacked a guesthouse used by the UN. They were later shot dead. Two Afghan security personnel and a civilian also died.
The Taliban said they carried out the attack, which comes 10 days before the second round of presidential elections.
Later, rockets were fired at the city's five-star Serena Hotel.
'Very dark day'
The UN condemned the "brutal" attack on the guesthouse in the Shar-i-Naw district and said it remained "committed to Afghanistan".
The head of the UN mission, Kai Eide, said this was a "very dark day" for the UN and that the deaths were a "loss to each and every member of the UN family here in Afghanistan".
But he added: "This attack will not, I repeat, will not deter the UN from continuing its work to reconstruct a war-torn country and to build a better future for the Afghan people."
The attack on the private Bekhtar guesthouse, which is used by the UN and other international organisations, happened just before 0600 (0130 GMT).
The US embassy has confirmed one of the dead is an American.
Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack in a telephone call to the Associated Press.
He said three Taliban militants with suicide vests, grenades and machine guns had carried out the assault.
UN spokesman Aleem Siddique told the BBC there was gunfire and an explosion outside the building as UN employees tried to flee. Streets were cordoned off by police.
The three gunmen were shot dead and the incident ended at about 0830 local time.
It was not immediately known how many people were inside the guesthouse at the time. The building was gutted by fire.
One foreign Kabul resident told the BBC the attack involved multiple grenades and automatic weapons.
"I saw people on the roof [security guards] and one woman climbed down from a second storey balcony after she had stood screaming and shouting for about five minutes for someone to come help her. Much of the gunfire was random - security guards shooting at nothing," he said.
UN spokesman Adrian Edwards said: "This has clearly been a very serious incident for us. We've not had an incident like this in the past."
The US embassy condemned the attack, saying it was "shocked and saddened".
"Attacking civilian workers will not lessen our determination to support the Afghan people and their election process," the embassy said.
Afghan interior ministry spokesman Zemarai Bashary praised the effectiveness of the security operation and said he hoped this incident would not point to further attacks in the run-up to the voting.
"We are preparing to strengthen the vulnerable points and the security belt for the centre of the city," he told the BBC.
But the Taliban spokesman said they had threatened to target anyone working on the Afghan run-off presidential election between incumbent Hamid Karzai and Abdullah Abdullah.
"This is our first attack," he said.
In the attack on the Serena Hotel, one or two rockets were said to have landed in the compound's grounds.
No-one has been reported injured at the hotel, which is used by diplomats and other foreigners, but about 100 people inside at the time were taken to secure rooms as smoke filled the lobby.
The Serena was also attacked by militants in January last year, with seven people killed.
The BBC's Ian Pannell in Kabul says that given the huge number of security personnel in the city, it is difficult to see how security there could be increased further.
The UN is playing a leading role in organising the run-off election and our correspondent says it is clearly a tactic of the Taliban to prevent its staff from going about their business safely.
There has been heightened tension in Afghanistan following the first round of the presidential election, which was marred by widespread fraud.
