Hoover Dam

A transformer at Hoover Dam, one of the nation's largest hydroelectric power plants, exploded on Tuesday, 

Hoover Dam

causing a thick cloud of black smoke and the flames to be quickly extinguished and No one was injured in an explosion

Hoover Dam

The Electricity Administration said electricity generated from the Hoover Dam powers the 8 million people in Arizona, Nevada

Hoover Dam

The cause of the fire was under investigation and officials were working to determine the extent of the damage

Hoover Dam

to the transformer, one of 15 on the premises that controls the voltage of electricity sent to consumers.

Hoover Dam

"There is no risk to the power grid," said Jacklynn Gould, a regional director for the U.S. Bureau of Reclamation.

Hoover Dam

Gould said in a statement that the fire started around 10 a.m. and was brought under control within half an hour. 

Hoover Dam

This caught the attention of tourists who said they heard an alarm and felt the ground rumble beneath them.

Hoover Dam

William Herro, 13, of San Francisco, was on a viewing bridge with his parents when he saw the explosion and then heard a "big boom."