The blast highlighted the dangers in a country awash with weapons amassed during a quarter-century of fighting, first against occupying Soviet troops, then among Afghan factions and now in the insurgency that followed the ouster of the Taliban in late 2001 by a U.S.-led coalition.
Afghan and U.N. officials are trying to disarm militias, but face an immense task in a nation where warlords still command local loyalties and remain wary of each other and the U.S.-backed central government.
The weapons and ammunition that exploded were in a bunker under a warlord's house in Bashgah, a farming hamlet in the mountains of Baghlan province, 75 miles north of the capital, Kabul, authorities said. They said it was unclear what set off the explosion about 6 a.m.
An Interior Ministry spokesman, Latfullah Mashal, said the cache was hidden by Jalal Bashgah, a former commander of a militia brigade, apparently to conceal it from the U.N. disarmament program.
The provincial police chief, Gen. Fazeluddin Ayar, said Bashgah's house was among a half dozen flattened along with the mosque and that eight of the commander's relatives were killed or injured. Bashgah was not at home at the time, Ayar told The Associated Press.
Initial accounts reported the blast also injured more than 70 people, but Ayar said officers sent to the village in a mountain valley found only 13 were hurt.
Before the accident, the most deadly reported incident with arms involved the U.S. military, which lost eight soldiers in January 2004 when arms they were preparing to blow up exploded prematurely.
Mohammed Yusuf Faiez, director of the province's only hospital, in Pul-e-Khumri, said 11 of those injured Monday — six men and five women — were admitted for treatment, two of them in serious condition.
He said they told of being blown off their feet as they walked home from morning prayer — apparently at the mosque next to the commander's house.