The mountain lion was seen in a residential area near Del Mar Boulevard and Euclid Avenue.
A photo shared by the city shows the big cat posted up against an apartment complex on Euclid Avenue.
The mountain lion was first spotted around 11 a.m., though officials say they don't know when it first entered the neighborhood.
City officials say in the past 30 years, they don't recall a mountain lion ever coming that far south of the freeway, which is miles from the foothills.
Police surrounded the neighborhood, blocked it off and told residents to stay inside. Officials with the California Department of Fish and Wildlife responded to the scene and tranquilized the mountain lion so it could be safely removed from the neighborhood and released back in its natural habitat.
AIR7 video shows CDFW officials tending to the mountain lion after it was tranquilized.
The big cat was also fitted with a tracking tag, according to city officials.
"It had to cross through major intersections of traffic, assuming it had to get down here, south of the 210 Freeway, so it's miraculous that this animal wasn't harmed just by vehicle traffic or spotted prior to getting here," said Lisa Derderian, a spokesperson with the city of Pasadena.
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It did not appear that the adult mountain lion had ever been tagged. It's unclear if it is a male or a female.
In the past month, there were two other mountain lion sightings on the east side of Pasadena, close to the 210 Freeway.
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