Authorities and meat plant employees were able to round up and return 38 cows to the Manning Beef facility.
One animal was shot and killed by sheriff's deputies after it appeared to be charging at people in the neighborhood. Several members of one family were injured and treated at a local hospital.
The 40th remains missing as of Wednesday afternoon.
Cows charge at sheriff's deputies
Loose cows charge police, residents in Pico Rivera
The incident happened Tuesday evening when 40 cows were able to escape from the Manning Beef plant on Beverly Road, apparently when a gate was left open.
The cows wandered through the streets of Pico Rivera, mostly sticking together as they trampled bushes and roamed through traffic.
The sight was startling for local residents, who broke out their cellphones and watched, mostly staying a safe distance away.
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"This is a once-in-a-lifetime thing," said one man."I might not ever see anything like that again. It was pretty amazing to come and see a bunch of cows."
Some residents incurred damage to their property and vehicles.
"I felt bad for our neighbor," he added. "They were right there in their driveway. They messed up their mailbox."
At one point Los Angeles County sheriff's deputies were able to trap the rogue herd on a cul-de-sac on Friendship Avenue.
As two trailers from the beef plant arrived, the animals appeared to be reluctant, backing as far away from the trucks as they could against the front of homes on the cul-de-sac.
At one point, at least three cows charged through the perimeter and broke free, running out onto major roadways such as Beverly Boulevard.
Most of the cows were rounded up by 11 p.m. except for the one that was killed and the one that remains missing.
PETA is also weighing in on the incident, suggesting the cows who broke free should be allowed to keep their freedom.
"These cows' desperate bid for freedom should have been recognized by moving them to a sanctuary, where they could have bonded with other rescued cows, nursed their calves in peace, and lived out their lives just as you and I hope to do," said PETA President Ingrid Newkirk.
Manning Beef has not commented on the incident.