A transformer explosion Tuesday at Hoover Dam created a thick cloud of black smoke and quickly extinguished the flames

There were no casualties in the explosion in the transformer near the dam.

regional director of the US Bureau of Reclamation Jacqueline Gold,  said "There is no risk to the power grid,"

The regional director of the US Bureau of Reclamation said in a statement that the fire started around 10 a.m. and was extinguished within half an hour.

The cause of the fire was being investigated

The Western Area Power Administration said 8 million people living in Arizona, Nevada and Southern California depend on the flow of electricity produced at the Hoover Dam.

Officials were working to determine the extent of damage to one of 15 transformers on the premises, which regulate the voltage for electricity sent to customers.

The explosion occurred on the apron of a building of turbines located slightly below the base of the dam, about 25 miles southeast of Las Vegas.

Hoover Dam is one of the tallest concrete dams in America with a height of 726 feet.

Each of the 17 generators from this shutdown can supply electricity to 100,000 homes.