Belgian Prime Minister Guy Verhofstadt has declared a national day of mourning for the victims of Friday's gas explosion that killed at least 15 people and injured more than 100.
The prime minister visited the blast scene Friday, and King Albert cut short a vacation Saturday, to travel to the site at Ghislenghien, in southern Belgium.
Three area workers are still missing.
The blast sent flames and bodies high into the air and destroyed two adjacent factory buildings. Many of the victims' bodies were charred beyond recognition.
Officials say firefighters who had arrived to investigate a natural gas leak were among those killed. A high-pressure underground line carries natural gas from the Belgian port of Zeebrugge to France.