A group of suicide bombers attacked a district governor's office in eastern Afghanistan Thursday, killing three police officers and wounding at least two others.

Local officials said three attackers detonated their explosives outside the Samkani district center building in Paktia province, where district officials and local elders had gathered to discuss next week's “loya jirga” or traditional assembly in Kabul.

Two other militants tried to storm the building but were killed in the fighting with police.

The Taliban claimed responsibility for Thursday's assault, saying it will target anyone involved in the jirga.

The meeting next Wednesday will discuss the peace process with the Taliban, and a proposed strategic security agreement with the United States.

In southern Helmand province, a car bomb exploded near a NATO convoy, killing two Afghan civilians in the provincial capital, Lashkar Gah.

U.S. combat troops are set to complete their withdrawal from Afghanistan by the end of 2014. International forces have already begun transferring security responsibility to their Afghan counterparts.

Germany said Thursday it will start to withdraw its troops from the war-torn country early next year.

German Foreign Minister Guido Westerwelle and Defense Minister Thomas de Maiziere outlined the plan in a letter to parliamentary leaders. The ministers said that, at the start of 2012, they plan to reduce the contingent from the current 5,350 troops to 4,900, with a further 500 soldiers leaving the country by early 2013.