BOULDER CITY, Nev. (AP) — Police in Boulder City, Nevada, were called to the Hoover Dam after reports of an explosion Tuesday morning.

Videos posted on social media showed what appeared to be a fire or explosion in a building near the base of the dam. In one video, a woman can be heard saying an alarm was activated at the site and a nearby bridge was felt shaking under her feet.

Officials with the Bureau of Reclamation later confirmed there was a fire in a power transformer, but it was extinguished by personnel on site before fire crews arrived at the scene.

There were no injuries reported and the facility was still producing electricity.

Hoover Dam is located in the Black Canyon of the Colorado River on the border between Nevada and Arizona.

According to the federal Bureau of Reclamation, the dam is 726 feet (221 meters) tall and 660 feet (201 meters) at its base, as long as two footballs fields measured end-to-end.

As many as 20,000 vehicles a day drive across the 45-foot (14-meter) wide top of the dam, which is a National Historic Landmark.

The Associated Press contributed to this report.