The Marion County Sheriff’s Office on Monday identified the victim as Pamela Kreimeyer. She was killed at the party in Knoxville, about 40 miles southeast of Des Moines.

The sheriff's office said members of the Kreimeyer family were experimenting with different types of explosive material on Friday and Saturday in an attempt to record a gender reveal that could be posted on social media.

On Saturday afternoon, Kreimeyer and five other family members, including the expectant mother, gathered and placed gunpowder in the bottom of a homemade stand that was welded to a metal base plate, according to the sheriff's office.

The inadvertent "pipe bomb" exploded, "sending metal pieces flying" and Kreimeyer, who was standing 45 feet from the device, was struck with one of the metal pieces and killed instantly, the sheriff's office said.