Officers located the baby boy after workers heard the mother screaming in an alley and then saw her giving birth shortly before 1 a.m., according to the Ventura Police Department.
It happened behind a bakery in an industrial complex in the 4200 block of Transport Street. The employees then called 911.
Jaime Benavides, one of the workers who helped the baby, said he saw the woman give birth and saw the baby slip down into her pants.
He said the mother pulled down her pants, severed the umbilical cord and ran away. Benavides said that's when he took the baby boy out of the woman's pants and held him.
"When I saw the baby was still alive, I was relieved," he said.
According to investigators, the woman appeared to be homeless.
The baby appeared healthy and was transported to a local hospital for treatment, where the child was listed in stable condition.
Police conducted an extensive search for the woman but were unable to locate her.
A detailed description was not available. Investigators expressed concern that she might be in need of medical attention.
Authorities issued a reminder that California has a "Safe Surrender" program, in which a parent or person with lawful custody can safely surrender a baby confidentially, and without fear of prosecution, within 72 hours of birth, at various locations, including hospitals and fire stations.
More information and additional Safe Surrender locations are available at cdss.ca.gov.