A massive explosion tore through Venezuela's largest refinery on Saturday, killing at least 39 people and injuring more than 80 in South America's largest oil producer, officials said.
President Hugo Chavez declared three days of national mourning. This "affects us all, the great Venezuelan family, civilian and military", he said in a telephone call with members of his cabinet.
Vice President Elias Jaua, who traveled to the area in western Venezuela, said on state television late on Saturday that at least 39 people were killed by the explosion, up from the earlier death toll of 26.
He said that the dead included 18 National Guard troops and that six of the bodies had not yet been identified. Other officials said earlier that the dead included a 10-year-old boy.
Five of the injured remained in hospital and were being evaluated, while two were transferred to a burn unit in a neighboring state and the remainder discharged with minor burns.
Ordering a "thorough investigation" into the cause of explosion, the Venezuelan president pledged to help the people who have been displaced from their homes at the refinery complex, which also houses workers and their families, and in impoverished neighborhoods nearby.
Rafael Ramirez, the energy minister, said the explosion was triggered by a gas leak, the cause of which remained to be determined.
"The gas cloud exploded, igniting at least two storage tanks and other facilities at the refinery," he told state-controlled VTV television.
Ramirez said the explosion, which occurred after 1am, was powerful and caused "significant damage" not only to the plant, but also to nearby shops and homes.
Firefighters were able to bring the fire under control, though smoke was still billowing from the facility.
The energy minister said he expected production of the the 645,000-barrels-per-day facility, which makes up two-thirds of the world's second largest refinery complex, to resume within two days.
As far as fuel shipments, he said, "we won't have major effects."
Ramirez said nine storage tanks were damaged and that oil workers inspecting the damage along with troops would determine the cause of the gas leak.
Images in state media showed the flames casting an orange glow against the night sky. One photograph showed an injured man being wheeled away on a stretcher.
Vice President Jaua said earlier on his Twitter account that the military was deployed to the area and that air ambulances were dispatched to ferry the wounded.
Amuay is part of the Paraguana Refinery Complex, which also includes the adjacent Cardon refinery.
Together, the two refineries process about 900,000 barrels of crude a day and 200,000 barrels of gasoline. Venezuela is a major supplier of oil to the US and a member of the Organisation of Petroleum Exporting Countries.
OPEC certified in 2011 that Venezuela has the largest oil reserves in the world at 296.5 billion barrels, surpassing Saudi Arabia, the country with the largest refining capacity.