(CNN) -- A third oil tank has burst into flames at Venezuela's Amuay oil refinery while another has been extinguished, officials said.
Meanwhile, the authorities lowered the death toll from Saturday's initial explosion at the refinery to 41 from 48 after receiving duplicate reports of some deaths.
Oil and Mining Minister Rafael Ramirez reported the third tank's ignition on Monday.
On Tuesday, President Hugo Chavez tweeted that one of the first two tanks that had caught fire was no longer burning.
The president had visited the refinery on Sunday to survey the damage.
Speaking to reporters then, he said it was too early to speculate what could have caused the blast, which also injured more than 80 people.
"There was a leak. The gas formed a cloud and it exploded. We must investigate why," Chavez said. He declared three days of mourning.
The blast early Saturday damaged refinery infrastructure and ripped through nearby houses.
Among the dead were 18 members of the national guard and 15 civilians, Vice President Elias Jaua said, according to state-run VTV.
In total, 209 homes and 11 businesses were damaged, Jaua said.
The refinery -- one of the world's largest -- is part of the giant Paraguana complex in Falcon state.
Venezuela, a founding member of the Organization of the Petroleum Exporting Countries, is one of the world's largest oil exporters.
The nation has a refinery capacity of more than 1 million barrels per day, according to OPEC.
The organization said Venezuela's oil revenues represent some 94% of the country's export earnings, more than half of federal budget revenues and some 30% of gross domestic product.
The South American country ships a large percentage of its exports to the United States.
CNN's Esprit Smith, Kevin Gallagher and Marilia Brocchetto contributed to this report.