SIOUX CITY, Iowa (AP) — Authorities say manhole covers were sent flying by explosions resulting from an underground electrical fire in Sioux City.

Firefighters were sent to the scene around 6:30 p.m. Wednesday. Assistant Fire Chief Dan Cougill says the fire stemmed from a system failure and that a pressure buildup caused the explosions. No injuries have been reported.

The fire knocked out power in several downtown blocks.