The bomber was able to enter the office of Chahar Dara district chief Abdul Wahid Omarkhail by pretending to be looking for work, said provincial government spokesman Mabobullah Sayedi. The blast killed the chief along with a bodyguard and a village elder who was visiting at the time.
Five others were wounded in the explosion, said Sayedi and the district chief of police, Gulam Mohyuddin.
Only last month, Omarkhail told The Associated Press he narrowly missed being hurt when a roadside bomb exploded near his car.
Although the focus of the U.S.-led war is in southern and eastern Afghanistan, insurgents have been working to expand their influence in the north.
Security has been deteriorating in Kunduz and other northern provinces, where there are known hide-outs for the Taliban, al-Qaida and fighters from other militant factions, including the Haqqani network, Hizb-i-Islami and the Islamic Movement of Uzbekistan. NATO has sent more troops to the north and has been pushing harder into militant-held areas.
In a joint raid in Chahar Dara on Dec. 31, Afghan and coalition troops killed an insurgent identified by local officials as the Taliban's "shadow governor" of Kunduz. The Taliban have set up shadow governors in many provinces, claiming to be the legitimate authority in those areas.
In October last year, a powerful bomb killed Mohammad Omar, the governor of Kunduz and 19 others in a crowded mosque in neighboring Takhar province.
Omar was killed just days after he publicly warned of escalating threats from Taliban and foreign fighters across the north. If steps aren't taken to counter them, Afghan and coalition forces would face disaster, he had said.