A massive explosion at a weapons dump near an airfield in northern Afghanistan (search) killed five Afghans, while two German soldiers missing in the blast were presumed dead, officials said Sunday.

The blast was believed to be an accident and occurred Saturday in northern Takhar province as some of the weapons were being moved before being destroyed, the International Security Assistance Force (search) in Afghanistan said in a statement.

Interior Ministry spokesman Latfullah Mashal (search) said the five Afghans were working as porters carrying the arms to trucks.

A sixth Afghan was also wounded and along with an injured German was to be flown to Germany for treatment, said Maj. Joseph Bowman, an ISAF spokesman. He said the two missing Germans were presumed dead.

A fourth German soldier was also wounded, but only lightly, according to a statement issued from the German division's headquarters at Schwielowsee outside of Berlin. Some 2,250 German soldiers serve in the ISAF force.

The weapons were being stockpiled near the airfield in the town of Rustaq after being collected as part of a national program to disarm militias. Afghanistan is awash with weapons after a quarter century of war and U.N., U.S. and NATO (search) forces report the discovery of weapons caches almost daily.

Though a vast arsenal has been collected, officials estimate many thousands of tons of arms are still scattered across the country.

There have been a series of explosions of weapons dumps. Last month, a warlord's stockpile of explosives dating from the Afghan resistance against occupying Soviet troops in the 1980s detonated accidentally, flattening a half dozen houses and a mosque and killing at least 26 people.