Seven people remained unaccounted for a day after an explosion at a warehouse storing fireworks in Northern California, authorities said Wednesday.

A fire broke out in the warehouse just before 6 p.m. Tuesday, said Cal Fire in a statement Wednesday. The fire triggered an enormous pyrotechnics display along with flames and smoke in a largely rural area of Esparto, about 30 miles northwest of Sacramento, officials said.

The cause was still under investigation.

Officials did not immediately identity the people who were missing. Chief Curtis Lawrence of the Esparto Fire Protection District said at a news conference Wednesday afternoon that the warehouse had been reduced to a large debris field filled with “large pieces of shrapnel.” The scene was too dangerous for emergency workers to access, officials said.

“This is a very complex and risky scenario right now,” Lawrence said, adding, “I have not experienced something like this.”

Lawrence declined to identify the owner of the warehouse, but the city of Marysville, the city of Yuba City, Sutter County and Yuba County said in a joint statement that it was operated by Devastating Pyrotechnics.

Two people were injured in the fire, Lawrence said. They “received care and are OK now,” he added.

Relatives of the missing attended the news conference Wednesday and expressed dismay that more was not being done to find their loved ones.

A woman whom CBS News Sacramento identified as Syanna Ruiz confronted a Cal Fire spokesperson, accusing the authorities of not “focusing on the people who are stuck in the warehouse, possibly dead.” Ruiz, 18, said that her boyfriend and two brothers-in-law were among the missing and that the family had not received “any information.”

“I’d like to issue apologies for the situation that we’re all here in, wanting to collect that information,” the Cal Fire spokesperson, Jason Clay, said. “The reason we have not been on site to do that is because of the danger presented.”

Cal Fire said that while the fireworks warehouse was “owned by an active pyrotechnic license holder,” investigators would work to determine whether all of its operations were in line with license requirements.

“This type of incident is very rare,” Cal Fire said in its statement.

When firefighters arrived Tuesday evening, they found “numerous explosions and numerous wildfires throughout the area,” Lawrence said at a news conference Tuesday night. The fires covered about 80 acres, he said, adding that firefighters had those under control while crews battled the main blaze.

“The fire will take time to cool, and once it does, explosive experts must safely enter the site to assess and secure the area,” the Yolo County Sheriff’s Office said in a statement Tuesday night. The Sheriff’s Office urged people to avoid the area for at least several days.

The Sheriff’s Office announced a 1-mile evacuation zone around the warehouse and urged people to avoid the area. The evacuation order remained in effect Wednesday afternoon.

According to an archived version of its website, Devastating Pyrotechnics “has produced displays in the San Francisco Bay Area and other California venues for over 30 years.”

The website associated with Devastating Pyrotechnics was updated on Wednesday evening with a statement saying that the company’s focus will “remain on those directly impacted by this tragedy.”