A transformer exploded Tuesday at Hoover Dam, producing a cloud of thick, black smoke and flames that were quickly extinguished. No one was hurt and electricity continued to flow from one of the nation�s largest hydroelectric facilities, authorities said.

�There is no risk to the power grid,� according to Jacklynn L. Gould, the federal Bureau of Reclamation�s regional director for the Lower Colorado Region. The fire ignited around 10 a.m. and was out within a half-hour, she said.

Hoover Dam, located on the Nevada-Arizona border about 25 miles (40 kilometers) southeast of Las Vegas, is a popular tourist destination and some of the visitors captured the scene on video and quickly shared it on social media.

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.�

�A ton of black smoke just exploded in the air. It looked almost like a mushroom and then a fire followed,� said Herro, who posted cellphone video of it on TikTok. �I was really surprised and I started filming.�

The postings showed the explosion occurred at a building slightly downstream from the base of the dam. The complex is in the Black Canyon of the Colorado River.

The cause of the fire is under investigation and it�s not clear how extensive the damage was to the transformer.

According to the Bureau of Reclamation, the dam is the second-tallest in the U.S. at 726 feet (221 meters). Each of its 17 generators can supply electricity to 100,000 households.

As many as 20,000 vehicles a day drive across the wide top of the dam, which is a National Historic Landmark.

(AP)