It was the latest in a string of attacks this week across the country, where insurgents are seeking to destabilise the government of President Hamid Karzai ahead of the withdrawal of most international troops by the end of 2014.
The group in Kunduz was attending a ceremony yesterday for a tribal elder who had died the day before, officials said.
The district governor who died, Sheikh Sadruddin, had been in his position since 2002 and been active in the fight against the Taliban.
Enayatullah Khaliq, a spokesman for the Kunduz governor, said: "Officials were attending prayers in a mosque when a suicide bomber detonated his explosives."
Twenty people were also wounded in the morning blast, police said.
Afghanistan's north is generally considered one of the safer parts of the country but in recent years it has seen increasing militant activity, with several violent confrontations between the Afghan army and insurgents. The area is close to the border with Uzbekistan and Tajikistan.
No group immediately claimed responsibility for the attack, although suspicion is likely to fall on the Afghan Taliban who have been behind many assassinations in the country.
Government officials and aid groups working with government ministries and Afghan security forces have been targeted in reprisal killings this week in provinces previously regarded as relatively stable.
Six men who worked for a development programme were executed in western Herat, one of Afghanistan's more stable provinces with a prosperous private sector that is helping to drive the national economy.
The toll on security forces this week has also been high.
An ambush in western Farah killed 15 policemen and another four were killed in Ghazni in the east in a Taliban attack on an international military base.
Several soldiers were also killed in Helmand, a Taliban stronghold in the south.
Civilians, however, continue to bear the brunt of the war, with about 20 killed in attacks during the week, and more than 50 wounded in the Ghazni attack alone.
The latest blast came as it emerged Australian troops are under investigation for allegedly cutting off the hands of at least one dead militant in Afghanistan.
The Australian Broadcasting Corporation said the hands of at least one insurgent were brought back to the Australian base in Tarin Kowt in Uruzgan province to be fingerprinted.
Officials at the Australian Defence Force (ADF) confirmed it was investigating "an incident of potential misconduct" during a combined operation between Afghan National Security Forces and Australia's Special Operations Task Group in Zabul province in April, but released no details.
The ADF says the Afghan-Australian operation had been targeting an insurgent commander responsible for a key militant network operating in and around Uruzgan province.
Australian troops had killed four fighters in a battle there.
A statement from the Australian military added: "The ADF also takes all reasonable steps to ensure its operations do not breach Afghan customs or cause offence by inadvertently disrespecting religious beliefs or norms."
Australian troops have been stationed at Tarin Kowt since 2005.
Australia has an estimated 1500 troops in Afghanistan. Most are stationed in Uruzgan, with the remainder in Kandahar and Kabul provinces.