CARACAS, Venezuela – A huge explosion rocked Venezuela’s biggest oil refinery and unleashed a ferocious fire Saturday, killing at least 26 people and injuring more than 80 others in the deadliest disaster in memory for the country’s key oil industry.

Balls of fire rose over the Amuay refinery, one of the largest in the world, in video posted on the Internet by people who were nearby at the time. Government officials pledged to restart the refinery within two days and said the country has plenty of fuel supplies on hand to meet its domestic needs as well as its export commitments.

At least 86 people were injured, nine of them seriously, Health Minister Eugenia Sader said at a hospital where the wounded were taken. She said 77 people suffered light injuries and were released from the hospital.

Officials said those killed included a 10-year-old boy, and that 17 of the 26 victims were National Guard troops stationed at a post next to the refinery.

President Hugo Chavez declared three days of mourning in the country.

“This affects all of us,” Chavez said by phone on state television. “It’s very sad, very painful.”

Chavez said he ordered a “deep investigation” to determine what caused the explosion.

Vice President Elias Jaua, who traveled to the area in western Venezuela, said the authorities tried “to save the greatest number of lives.” Troops were deployed to the area

Officials said firefighters had controlled the flames at the refinery on the Paraguana Peninsula, where clouds of dark smoke were still billowing at noon.

Oil Minister Rafael Ramirez said the state oil company should be able to “restart operations in a maximum of two days.”

“We have sufficient supplies… in the entire country, and our production at the maximum to deal with any situation in our domestic market,” Ramirez said. “In that sense, we won’t have major effects.”

An official of the state oil company, Petroleos de Venezuela SA, said the country also has enough supplies on hand to guarantee its international supply commitments. The official spoke on condition of anonymity because he wasn’t authorized to speak publicly about the matter.

The blast occurred about 1:15 a.m. when a gas leak created a cloud that ignited, Ramirez said. An adjacent National Guard post was severely damaged by the blast, along with nearby homes, he said.

“That gas generated a cloud that later exploded and has caused fires in at least two tanks of the refinery and surrounding areas,” Ramirez said. “The blast wave was of a significant magnitude.”

Images in the early hours after the explosion showed the flames casting an orange glow against the night sky. One photograph showed an injured man being wheeled away on a stretcher.

“The areas that had to be evacuated were evacuated,” Falcon state Gov. Stella Lugo said on television, according to the state-run Venezuelan News Agency. “The situation is controlled. Of course there’s still a fire rising very high, but … the specialists tell me there is no risk of another explosion.”

Ramirez said a panel was being formed to investigate the cause of the gas leak. A prosecutor also was appointed.