Rescuers are searching for survivors after a powerful blast in Jalalabad killed at least 26 people and knocked out power to the eastern city, stoking fears about Afghanistan's volatile security climate.
Provincial officials said today stored explosives at the Afghan Construction and Logistic Unit (ACLU) on the outskirts of Jalalabad could have accidentally detonated, though military officials earlier speculated it was a terrorist bomb.
The massive explosion ripped apart dozens of mud-built homes near a hydro-electric dam, on Friday injuring at least 80 people, Kabul Radio said.
Afghan rescue teams had found 13 bodies by Saturday morning, laboriously digging through piles of rubble with rudimentary tools, rescue official Mr Haji Nasrullah Baryalai said.
"Since dawn, people have resumed their search to see if they can find any survivors, as we don't know whether more people are caught under collapsed walls and timbers of houses or not," Mr Baryalai told reporters.
State-run Kabul television put the death toll at 26.
Mr Baryalai said dozens of wounded people were being treated in the city's hospital.
Power was cut throughout Jalalabad after the blast damaged the dam.
Mr Baryalai said the explosion went off inside a room storing explosive devices used for road construction.
"For dynamiting ridges and hindrances along the roads, ACLU needed the explosive materials...," he said.
"There is a strong possibility that the blast was not an act of sabotage. Investigation continues to find if it was a sabotage incident, but so far we have found no clues to back up this speculation," Mr Baryalai added.
The US military quoted initial reports from US officials in Jalalabad as saying a truck bomb caused the blast.
Jalalabad, about 110 kms (70 miles) east of Kabul near the border with Pakistan and the capital of Nangarhar province, has long had a reputation as a centre for heroin production.