US / Northrop Grumman Blast Destroys Building at Utah 'Rocket Ranch' Sheriff's office says initial investigation found no fatalities at Northrop Grumman test site By Newser Editors and Wire Services Posted Apr 16, 2025 6:15 PM CDT Copied This photo provided by the Box Elder County Sheriff's Office shows the wreckage from an explosion at Northrop Grumman's remote rocket testing site on Wednesday, April 16, 2025, in Promontory, Utah. (Box Elder County Sheriff's Office via AP) An explosion at Northrop Grumman's remote rocket testing site in northern Utah destroyed a building Wednesday. Officers found no injuries or fatalities in their initial investigation of the wreckage, according to the Box Elder County Sheriff's Office. "However, as with all ongoing investigations, details may change," the sheriff's office said. Emergency crews responded to reports of a loud blast and a dark plume of smoke rising over the rangelands at 7:38am, the AP reports. It was not immediately clear which building was destroyed and what its purpose was. The aerospace and defense company maintains a large presence in Utah, where it manufactures and tests solid rocket motors. The site near Promontory, around 32 miles west of Brigham City, is known as the "Rocket Ranch," KSL reports. Fox 13 reports that the building destroyed in Wednesday's blast doesn't appear to be the one where the company combines chemicals to make rocket boosters used in space programs. (More Northrop Grumman stories.) Report an error