Police initially reported a fire had broken out near 17th and Capitol streets. Omaha Police Sgt. Jason Menning tweeted the fire was started by a power transformer used by the Omaha Public Power District. At 17th and Capitol is the Doubletree Hotel and First National Bank. Omaha Scanner posted to Facebook saying security footage from First National Bank caught the moment on camera, and a security guard says he heard the explosion then saw black smoke. They say crews continued reporting explosions once they arrived on scene. The Omaha Fire Department's Acting Battalion Chief Mickey McLaughlin told WOWT-TV 6 News they're unsure what caused the transformer to explode, but says it could be old electrical equipment.