Shots rang out inside the themed store at the Solano Town Center mall in Fairfield, Calif., at around 8:30 p.m. on Friday, Fairfield Police Chief Dan Marshall said during a press conference, The New York Post reported.
One person was pronounced dead at the scene, while six others were rushed to a hospital, where three are listed in critical condition.
Police did not reveal any description of the suspected shooter and did not confirm if there were more than one suspect.
A motive behind the shooting was not revealed.
“This is still a very active crime scene. Detectives are speaking with witnesses and diligently working to identify the suspect responsible for this horrific shooting,” police said in a press release.
The store was open and filled with customers when the shooting began, sending shoppers fleeing for their lives.
“Well, she just told me she heard some shots and the people running, yelling and crying already,” one witness described what his wife experienced to KCRA.
The man said his wife heard roughly seven shots ring out before bystanders raced to safety.
The temporary, pop-up Halloween store took over the space once occupied by Best Buy at the mall that holds approximately 130 stores.
The shooting at the Fairfield Spirit Halloween store follows hours after a man was fatally shot in a Michigan store.
The unidentified 21-year-old was found suffering from multiple gunshot wounds at the store in Madison Heights just after 2 p.m., according to the Madison Heights Police Department.
Another 21-year-old, suspected in the killing, was attacked by bystanders and taken to the hospital while in police custody.