Four armed militants launched a suicide attack on a U.S.-run base in northeastern Afghanistan early Saturday, blowing themselves up and killing two Afghan civilians.

Local officials said the bombers targeted the base of the U.S. Provincial Reconstruction Team in Panjshir province. They said two security guards were wounded.

The Taliban has claimed responsibility, saying the militants attacked on foot and with an explosive-filled vehicle.

In southern Kandahar province, two militants were killed and three wounded when the bombs they were assembling prematurely exploded.

NATO said two of their service members were killed in two separate insurgent attacks in southern Afghanistan Saturday.

And a NATO helicopter with 12 passengers and five crew members made a forced landing late Friday during a mission in the south. NATO said no one on board was injured and it appeared that the incident was the result of a mechanical issue, since there was no insurgent activity in the area.