Up to 19 people are believed to have died following the collapse of three buildings in Taiz, Yemen's second-largest city.
The buildings collapsed following an explosion in a dynamite warehouse under one of them, sources told Al Jazeera's correspondent in south Yemen.
At least nine bodies were pulled from the rubble on Tuesday and rescue workers were looking for 10 more believed buried and feared dead.
Fifteen people were also reported injured and taken to hospitals.
Initial findings gave no indication the explosion was anything other than an accident, an official said.
The explosives were stored in the basement of a four-storey building that was reduced to rubble in the residential al-Masbah area of Taiz.
Witnesses told the German Press Agency DPA that the pre-dawn explosion left eight families homeless.
They said the warehouse was owned by an arms dealer and was used for road construction in the mountainous Taiz province.
"The explosion tore apart three buildings," Muhammad Saeed, a witness said by phone. "Many people are still under the wreckage."
Security officials said search-and-rescue operations were continuing.