A roadside bomb killed a district police chief and three other officers after striking a police vehicle in northern Afghanistan on Thursday, dpa reported.
The bomb went off in the Kashinda district of Balkh province, northern police spokesman Lal Mohammad Ahmadzai said.
He said the district's administrative officer was wounded in the explosion.
In neighboring Kunduz province, a bomb planted on a road close to a provincial governor's residence was exploded by security forces after they were unable to defuse it, police spokesman Sayed Sarwar Hussaini said, adding that no one was harmed in the blast.
Separately, NATO-led International Security Assistance Forces (ISAF) said one of their military choppers crashed in eastern Afghanistan on Thursday.
Alliance spokesman Major Adam Wojck said that the crash caused no injuries to the two crew members on board.
"There is an ongoing operation. We don't know if there was enemy activity at the site of the crash."
Taliban militants posted a statement online claiming responsibility.