Fire crews responded to a JC Penney store in Antioch where an unknown substance was released and sickened nearly a dozen people, according to the Contra Costa Fire District.
Fire officials reported 11 people were affected by the release, and two were transported to a hospital. The initial call came at about 6:30 p.m.
A hazmat team also was called to the scene, fire officials said. They said the release was confined to the JC Penney store, and hazmat crews were preparing to enter the building a little after 8 p.m.
The nature of victims' illnesses was not provided. One adult was transported immediately with breathing problems, fire officials said. The second transported patient was a minor, they said. All other victims declined to go to the hospital.
No further details were available.