The Hoover Dam has been constructed on the Colorado River.
An explosion shocked the visitors at the Hoover Dam, one of the largest hydroelectric facilities in United States' Nevada, on Tuesday. A footage of the incident showing a thick cloud of black smoke and flames was posted online by one of the tourists who was present at the site when the explosion took place. Boulder City, where the dam is located, tweeted that the fire department received an emergency call and rushed a team to check the incident at the dam.
In the video posted on Reddit, a witness can be heard saying, "My goodness, something has just blown up." The same video was posted on Twitter too by user Kristy Hairston who said she was "touring the Hoover Dam" when she "heard an explosion".
Boulder City later tweeted that the fire was extinguished before the fire department arrived on scene.
In a statement, Lower Colorado Regional Director at the Bureau of Reclamation Jacklynn Gould said the fire was reported in one of the transformers installed at the dam.
"There is no risk to the power grid," added Ms Gould.
No one was injured in the explosion, which was reported near the base of the dam. The officials are working to determine the extent of damage to the transformer, one of the 15 installed at the complex, reported ABC News.
The Hoover Dam has been constructed on the Colorado River, on the border between Nevada and Arizona. It was constructed between 1931 and 1936 during the Great Depression and was dedicated to the nation by the President Franklin D Roosevelt in 1935.