An Afghan security official says a suicide bomber has killed three police officers and a civilian in the southern part of the country.
Helmand province's police chief Mohammad Hussein Andiwal said the bomber blew himself up Friday near a police vehicle in the provincial capital, Lashkar Gah. Three people were wounded.
No one has claimed responsibility for the attack.
Helmand has been the site of some of the fiercest fighting between coalition forces and insurgents. It is also the biggest opium producing region in the world.
In other violence, NATO officials said a civilian died Thursday in eastern Kunar province when his truck appeared to hit a roadside bomb while driving as part of a NATO convoy.
Later Thursday, a NATO patrol shot at a vehicle in southern Kandahar province, killing one civilian and wounding three others.
NATO said the patrol acted in self-defense after the driver did not heed the soldiers' warnings to stop.
Last week, a U.S.-based terrorist monitoring organization, SITE, said the Taliban had announced the beginning of a spring offensive against coalition forces in Afghanistan.
Some information for this report was provided by AFP and AP.