At least 11 people were wounded in the strike, whose victims included several civilians.
The apparent assassination was the latest attack in a particularly bloody week in Afghanistan, further underscoring the tenuous security situation here.
No group immediately claimed responsibility for Friday's attack, but suspicion fell on the Afghan Taliban. The militant group has escalated its actions in recent months to take advantage of the drawdown of U.S.-led foreign troops, who handed over security for the country to Afghan forces two months ago.
The bomber struck in Dashi Archi district of Kunduz province. Hussaini said the district chief, Sayed Sadruddin, was with tribal leaders and others at a memorial service for someone who had died earlier.
There are currently about 100,000 troops from 48 countries in Afghanistan with the U.S.-led International Security Assistance Force, 60,000 of them American. By the end of this year, the NATO force will be halved, and all foreign combat troops are expected to be gone by the end of next year.
Because of the drawdown, much is riding on the abilities of the fledging Afghan security forces, which now number about 352,000.
Afghan and coalition officials have warned that the Taliban would intensify the tempo of their attacks following the Muslim Holy month of Ramadan, as they try to take advantage of the two or three months left of good weather before the harsh Afghan winter sets in. The traditional fighting period lasts from March until the end of October.
The Taliban have already staged multiple attacks this week, leaving dozens dead and even more wounded.
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