An explosion of unknown origin has rocked the Hoover Dam complex.

Video from the dam on Tuesday showed fire and smoke rising from the turbine house on the Arizona side of the Colorado River, at the foot of the 726-foot tall dam.

Units from the Boulder City Fire Department are responding to the blaze.

‘Boulder City Fire Department is en route to an emergency call at Hoover Dam. No further information is available at this time,’ officials said in a statement.

Developing story, more to follow.