KANDAHAR, Afghanistan (AP) — A suicide bomber slammed a pickup truck packed with explosives into a checkpoint in a neighborhood housing U.N. and international aid group offices in the southern city of Kandahar on Monday, killing four people including the district police chief, Afghan officials said.

Immediately after the blast, three insurgents rushed into the neighborhood and seized control of at least one building, sparking a gunbattle with Afghan and NATO forces, Kandahar police chief Gen. Abdul Razzaq said. The firefight lasted more than two hours before the militants were shot dead.

The combined bombing and assault was the second major attack in three days to target foreigners or NATO troops in the country, and spotlighted the insurgents’ ability to continue to carry out major attacks despite a 10-year NATO campaign against them. The U.S.-led coalition is gradually handing over security responsibilities to its Afghan counterparts and plans to withdraw its combat forces by the end of 2014.

“Despite the insurgency’s failures this past year, it remains capable and, enabled by safe havens in Pakistan, continues to contest (Afghan and NATO) progress in some parts of the country,” German Brig Gen. Carsten Jacobson, a coalition spokesman in Afghanistan told reporters in Kabul.