A strong odor of unknown origin was traveling through Orange County Thursday night, officials said.
The fire departments in Huntington Beach and Costa Mesa both fielded reports concerning the chemical smell, and Huntington Beach officials said it had appeared in several other cities as well.
"Fire crews responded to investigate and the source is unfounded," the Costa Mesa Fire Department said in a tweet.
Several O.C. residents contacted KTLA to voice their concern. Brynne Palmer, who lives in Costa Mesa, said her eyes began to water when she stepped out to walk her dog.
The agency advised residents to close their windows and doors.
The smell could also be reported to the South Coast Air Quality Management District at 1-800-288-7664. Any abnormal medical symptoms should be reported to 911, firefighters said.
KTLA's Anna Albaryan contributed to this report.