A huge explosion rocked Venezuela’s biggest oil refinery early Saturday, killing at least 19 people and injuring more than 50 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.

Those killed included a 10-year-old boy, and at least 53 people were injured, Falcon state Governor Stella Lugo said on state television. She said firefighters had controlled the flames at the refinery on the Paraguana Peninsula in western Venezuela, where large clouds of smoke were rising.

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

The blast occurred after 1 a.m. when a gas leak created a cloud that ignited, Oil Minister Rafael Ramirez said. Some nearby houses were damaged by the blast, he said on television.

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

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.

Mr. Ramirez said oil workers will determine what caused the gas leak and were inspecting the damage along with troops. He said supplies of fuel had been cut off to the part of the refinery that was still in flames.

Troops were securing the area at the refinery, Ms. Lugo said.

Vice-President Elias Jaua said on his Twitter account that the military was deployed to the area and that air ambulances were dispatched to ferry the wounded. The Defence Minister was traveling to the refinery along with Mr. Ramirez and other officials, Mr. Jaua said.

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. It was unclear to what extent the explosion might affect oil shipments from Venezuela, a member of the Organisation of Petroleum Exporting Countries.

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