Hoover Dam transformer fire 

A transformer of hydroelectric facilities at Hoover Dam has exploded.

The explosion had caused thick clouds of black smoke.

After that the flames arose and the employee extinguished it as soon as possible.

No personnel were injured in this explosion.

Now the engineers are investigating the cause of the fire.

Some officials are investigating how much damage was done to the transformer.

"There is no risk to the power grid,"

said a director of the US Bureau of Reclamation.