A third crude tank caught fire and collapsed at Cuba’s main oil terminal in Matanzas, the province’s governor said, as an oil spill spread flames from a second tank that caught fire two days earlier in the island’s biggest oil industry accident in decades, Reuters reported.

The sky as far away as Havana was darkened by huge columns of fire and thick black smoke. An explosion rocked the area just before midnight when one tank collapsed, and another at noon when another imploded.

As a result of Saturday’s explosion at the second storage tank, one firefighter died and 16 people were missing. There was a threat to a fourth tank, but it had not caught fire. The majority of Cuba’s electricity is generated by oil.

During the weekend, Cuba had fought off the raging flames with the help of Mexico and Venezuela, but late on Sunday, the second tank collapsed, spreading the fire, said Mario Sabines, governor of Matanzas province, about 60 miles (130 km) from Havana.

In terms of crude oil and fuel imports, Matanzas is Cuba’s largest port. Electricity is generated on the island primarily by Cuban heavy crude, fuel oil, and diesel stored in Matanzas.

Due to low water pressure in the area, the country’s most important power plant, located less than a mile from the fire, was shut down on Monday noon.

More than 90% of the fuel used by the electric system was in danger, according to Jorge Pinon, director of the Latin America and Caribbean Energy and Environment program at the University of Texas at Austin.

“The key questions now are where Cuban crude oil production will go to generate fuel for electrical use as it is only connected by pipeline to Matanzas,” Pinon said, adding the facility has an installed capacity of 2.4 million barrels.

According to Pinon, the tanker might be required to transfer its cargo via ship-to-ship operations since Matanzas is the only terminal with the ability to receive large vessels. This would allow the crude to be refined at the Cienfuegos or Havana refineries, “but it is not clear Cuba has the capacity to do that,” Pinon said.