Investigators released the names on Saturday of the seven people who were killed in a massive pyrotechnics facility explosion in Northern California that took place days before the Fourth of July.

       The blast occurred in Esparto, about 40 miles from Sacramento, on July 1, triggering a series of massive explosions, according to the fire department.

       Seven people were killed in the explosion according to the medical examiner: Angel Mathew Voller, 18, of Stockton, Jesus Manaces Ramos, 18, of San Pablo, Jhony Ernesto Ramos, 22, of San Pablo, Joel Jeremias Melendez, 28, of Sacramento, Neil Justin Li, 41, of San Francisco Carlos Javier Rodriguez-Mora, 43, of San Andreas, and Christopher Goltiao Bocog, 45, of San Francisco.

       Cal Fire of the State Fire Marshal said it believes the facility belongs to a licensed pyrotechnics operator. Investigators are working to determine if the operation complied with California's pyrotechnics regulations and federal explosive storage requirements.

       "This type of incident is very rare," Cal Fire officials said last week.

       The investigation remains ongoing.