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

A fire broke out in the warehouse just before 6 p.m. Pacific time on Tuesday, Cal Fire, the state’s firefighting agency, said in a statement on Wednesday. The fire triggered an enormous pyrotechnics display along with flames and smoke in a largely rural area of Esparto, Calif., 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 on 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,” Chief Lawrence said, adding, “I have not experienced something like this.”

Chief 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. The company’s website and social media accounts did not appear to be active on Wednesday afternoon and company officials could not be reached for comment.

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