Four security guards have been killed after three suicide bombers attacked a guest house frequented by foreigners in Kunduz province of northern Afghanistan, police officials say.
"Ten people, including civilians and an Afghan police officer, were wounded in the early morning attack," Abdul Rahman, senior Kunduz police official, said on Tuesday.
Mubobullah Sayedi, a spokesman for the governor of Kunduz province, said one of the gunmen blew himself up outside the two-story building shortly after dawn, while two other attackers rushed inside.
Security forces battled for two hours before the attackers were eventually killed.
It was not immediately clear if foreigners were among the wounded, but those staying at the guest house escaped through the rear of the building.
Sarwar Husseini, a provincial police spokesman, said German aid workers often stayed in the house, but the identity and number of foreigners staying there at the time of the attack was not clear.
The building burned and several nearby buildings were damaged. Flames could be seen shooting up an exterior wall as police contained the area.
"We heard a very big explosion that shook all of Kunduz," Ahmadullah, a 30-year-old shopkeeper in Kunduz, who lives about 10 meters from the building, said.
The Taliban has claimed responsibility for the attack.
Zabiullah Mujahid, a spokesman for the Afghan fighters, said in a text message to the AP news agency that the bombers had attacked a "German intelligence centre and security company".
Deadly six months
Fighting has been focused in southern and eastern Afghanistan, but the Taliban has been conducting a rising number of attacks in the once-peaceful north.
Last month, a vehicle carrying the deputy governor of Kunduz province struck a roadside bomb, injuring three of his bodyguards.
Al Jazeera's Bernard Smith reports on security in Kabul since the June hotel attack
In May, a suicide bomber infiltrated a high-level meeting in neighbouring Takhar province and killed northern Afghanistan's top police commander, General Daoud Daoud, provincial police chief Shah Jehan Noori and two German soldiers.
Violence is at its worst in Afghanistan since US-backed international forces toppled the Taliban government in late 2001.
With at least 1,462 deaths, the first half of this year has been one of the deadliest for civilians, according to a UN report in July.
A gradual transition of security control to Afghan forces began last month when some areas were handed over by the NATO-led International Security Assistance Force.
Afghan forces are due to take full control across the country by the end of 2014.
Ever since President Barack Obama announced the withdrawal of US "surge" troops in June, the Taliban has intensified attacks against government installations.
In the past month gunmen have carried out a string of killings of high-profile southern leaders, including President Hamid Karzai's younger brother, Ahmad Wali Karzai, and other senior government officials.