A damning new civil grand jury report points the finger at Yolo County officials who, the report says, knew about the illegal fireworks storage facility in Esparto for years but failed to enforce safety codes, leading to last July's deadly explosion.

The dramatic, cinematic explosion at a fireworks company's storage facility in Esparto on July 1, 2025, which took the lives of seven men, could have been prevented through simple code enforcement. That is the conclusion of a new civil grand jury report, which comes amid a simultaneous criminal investigation by the Yolo County District Attorney's Office, and a separate investigation by Cal Fire. And it's a conclusion that is likely to bolster wrongful death suits filed against the county by the families of the victims.

The 32-page report is titled "Esparto Fireworks Explosion: Officials Knew, None Acted," and as KCRA reports, it points to multiple points of failure by government officials, and to potential conflicts of interest and "blind eye" policies that led to the tragic fireworks conflagration.

It also suggests that multiple elected officials and law enforcement were aware that the fireworks facility existed, and it was allowed to freely operate despite a county-wide ban on fireworks.

"Inexplicably, no code enforcement occurred, even though all dangerous fireworks had been banned by ordinance throughout rural Yolo County since 2001,” the report states. “In the absence of official oversight and enforcement, unmitigated expansion of the fireworks businesses operating at the site in Esparto led directly to death and destruction from the Esparto Fireworks Explosion."

The ironically named Devastating Pyrotechnics was a business that grew out of a hobby of longtime Esparto resident and local farmer Jerry Matsumura. As the report recounts, residents of the small town of Esparto (pop. 3,572) were familiar, for decades, with the local, unofficial fireworks displays that went off from Matsumura's farm in the spring and fall. The spring show was for Matsumura to test out new products — part of a sideline business that grew out of his own hobby, selling professional-grade fireworks to local towns and cities. And the fall show was to dispose of whatever he had left in his inventory after summertime sales were finished.

After Matsumura died in 2015, the business passed on to business partner Kenneth Chee — who we learned last year was a San Francisco resident — and the property passed on to Matsumura's daughters, Rieko Matsumura and Tammy Machado, along with Machado's husband Sam Machado. And herein lies the conflict of interest — all three were employed by the Yolo County Sheriff's Office at the time of the explosion. (Rieko Matsumura has since retired from the department.)

The fireworks business appears to have grown significantly over the last decade, and not without the knowledge of people high up in county government. The report points to a June 2, 2022 tip given to a county Building Services department official that two fireworks businesses were operating on the property.

Officials reported responded that Esparto fire officials and the ATF had signed off the facility as having storage for both dangerous and "safe and sane" fireworks. And a new building added to the site was reportedly represented to the county as being storage for almonds.

Then there's this damning detail: "Following the site visit, the County Community Services Department took steps toward a possible enforcement action against the property. But within days, this conversation about the site – at least in email records provided by the County – abruptly ceased. The department failed to take any action, and the fireworks business continued to quietly operate and even expand."

The grand jury points to multiple points of failure in the system, including an assumption by local officials that the state was responsible for monitorying the facility, and the fact that the county’s building and code enforcement divisions were understaffed. Also, the grand jury said they heard from sources that code enforcement was "a low priority" for the county board of supervisors, especially on farmland.

The Yolo County Board of Supervisors responded in a press release Thursday, saying, "While the Civil Grand Jury report raises important issues related to communication, coordination, and emergency response, it represents one part of a broader, ongoing process."

And, they add, "The Board of Supervisors respectfully disagrees with the report’s suggestion that the County does not take code enforcement seriously. While funding levels have varied historically, the Board has consistently supported and funded the County’s code enforcement program in recent (compared to previous) years and continues to recognize the essential role it plays in protecting community health and safety."

The explosion killed seven men who were working at the fireworks facility in the busy days before the Fourth of July. They were Joel Jeremias Melendez, 28, of Sacramento; Jesus Manaces Ramos, 18, of San Pablo; Jhony Ernesto Ramos, 22, of San Pablo; Angel Mathew Voller, 18, of Stockton; Carlos Javier Rodriguez-Mora, 43, of San Andreas; Neil Justin Li, 41, of San Francisco; and Christopher Goltiao Bocog, 45, of San Francisco.

After seeing the grand jury report, Lupe Mendoza-Melendez, the mother of Joel Melendez, tells KTVU, "I didn't know it was going to be that deep, that many people could have prevented it. I didn't know that many people could have saved my son, saved me, because part of me died with him."

Stay tuned as we await the results of the criminal probe still being pursued by the county DA's office.

Related: Seven Victims Identified In Yolo County Fireworks Warehouse Blast, Four Were Bay Area Residents