Los Angeles (CNN) -- The urban jungle of greater Los Angeles is wrangling with a mystery caught on video: Just what kind of beast is lurking in the pre-dawn darkness?
So far, authorities have ruled out a mountain lion.
But could it be an African lion, just 25 miles outside downtown Los Angeles, in the suburb of Norwalk?
Or, as some wiseacres assert on Norwalk's Facebook page, could it be the mythic chupacabra, the dreaded "goat sucker" fabled in Latin America?
Norwalk city officials are taking the matter seriously -- that a mysterious animal has been on the loose since it was last seen on July 29 just before 4 a.m., according to a time stamp on the video.
Officials are calling it "a large wild cat," the city's website says.
A residential surveillance video shows what appears to be an aged lion with a long, curving tail. It saunters behind a parked vehicle and then appears in an illuminated area, clearly showing an overall image of the animal. A resident mistakenly reported it as a "mountain lion," city officials said.
"Animal was not aggressive -- moves slowly as if aged," city officials said on their Facebook page.
The California "Department of Fish and Wildlife confirmed that the large cat-like animal captured on surveillance video is NOT a mountain lion," city officials added. "Department officials still cannot definitively identify the type of animal. They will continue to investigate."
Beneath that notice was one comment that described an uneasy city: "Don't know what's scarier, that it was a mountain lion, or that 'Department officials still cannot definitively identify the type of animal.' "
Police and sheriff's deputies have stepped up their patrols in Norwalk, located among a knot of smaller cities southeast of downtown Los Angeles. Authorities are providing information to residents on what to do if they see the animal.
The neighborhood where the big animal was sighted is at least 20 miles from typical foothill habitat for mountain lions and is near the junction of Interstate Highways 5 and 605, CNN affiliate KTLA said.
One lion expert told The Los Angeles Times that the animal appeared to be an African lion, but another expert told the newspaper that he thought it was a leopard. The video appears to distort the size of the animal, which could be no more than 2 feet high, the height of a sign that it passes, state game warden Don Nelson told the newspaper.
"It appears, in my opinion, to look like a dog, maybe an older pit bull mix," Nelson said in an interview with KTLA.
But he said "anything is possible."
In the meantime, area residents continue to speculate.
"Proportions aren't correct for an African lion or cheetah, but it's definitely a big cat," one woman posted on Norwalk's Facebook page. "By the large size of the head and thickness of the body, I'd say this animal is a young adult jaguar. They've been trying to re-establish themselves in the Southwest for some time."