Los Angeles firefighters and a hazardous-materials team responded to a one-story building in the 20700 block of W. Marilla Street for a report of an unknown "vapor cloud" coming from behind the building, according to LAFD.
LAFD evacuated at least 31 people from the building as a precaution. Paramedics evaluated eight people, according to LAFD. Seven of them declined hospital transport.
A 50-year-old man was taken to the hospital with minor medical complaints, LAFD said.
Firefighters were keeping people away from the area.
No further details were immediately known.
The cause of the vapor is unknown.