A mysterious explosion rocked the Hoover Dam around 10 a.m. PDT on Tuesday morning and the fiery plume was caught on bystander video. Officials confirmed the fire was extinguished approximately 30 minutes after the explosion took place.
Twitter user Kristy Hairston first posted the video that began circulating Twitter. “Touring the #hooverdam and heard an explosion,” she said.
Nearby Boulder City Fire Department confirmed shortly after that emergency responders were en route to “an emergency call at Hoover Dam.”
However, the department said the fire was extinguished before responders could arrive on scene.
An additional video circulating social media showed another angle of the fire.
The U.S. Bureau of Reclamation posted an update at 11:26 am PDT saying “the A5 transformer at Hoover Dam caught fire.” Fire officials at the bureau and Hoover Dam’s fire brigade extinguished the blaze 30 minutes later.
“There are no injuries to visitors/employees. There is no risk to the power grid. Power is still being generated from the powerhouse,” the bureau said.
It’s not yet clear what caused the explosion.
Hoover Dam was built in the 1930s to dam the Colorado River, thus creating Lake Mead. The largest reservoir in the nation, Lake Mead supplies water to millions in Nevada, Arizona, California, and Mexico.
Hoover Dam is also home to one of the world’s largest hydroelectric power plants, which also supplies power to Nevada, Arizona, and California.