The Hoover Dam, a major tourist attraction on the border between Nevada and Arizona, was the scene of an explosion.
There are videos that show pieces of machinery going up in a blast and a huge cloud of smoke.
In her video, Hairston said something blew up while she was at the dam.
The fire was extinguished before the Boulder City Fire Department arrived.
We heard more about the incident about an hour after we first heard about it.
The Bureau of Reclamation, a federal agency that oversees water resource management, said in a statement that a transformer caught fire. The fire was put out by the Hoover fire brigade.
There are no injuries to visitors or employees. The power grid is safe. The power is still being produced.
One of the largest hydroelectric plants in the US is the Hoover Dam, which is located in Nevada.
Seven million tourists visit the dam every year, making it the most visited dam in the world.
The incident was small and contained so nobody got hurt.
The bureau is investigating the cause of the fire and will give more updates.
China says it is 3D printing a 590 foot hydroelectric dam.