Authorities in Southern California responded to a slow leak from a chemical tank on Tuesday but quickly got it under control.
The substance and the leak's origin remain unknown, Los Angeles County Fire Department spokesperson Kaitlyn Aldana said.
Three people on scene declined transport to a hospital, she said.
Photos posted to social media showed what appeared to be an orange haze or mist in the sky.
La Habra Mayor Jose Medrano urged residents to shelter in place and said some streets were being evacuated.
The area is a mix of residential neighborhoods and industrial warehouses about 10 miles (16 kilometers) north of Anaheim.
