The department called an unusual 7 p.m. press conference to announce that Officer Sergio Alvarez (left), who had been with the city of West Sacramento since 2007, allegedly had carried out the acts while performing uniformed patrol duties.
The investigation identified six female victims ranging in age from 20 to 47 years old, police said.
Alvarez, who has received termination papers from the department, is in the Yolo County Jail, the department said in a release. He was taken into custody by both the West Sacramento and Sacramento Police departments.
The release said Alvarez used his position as a police officer to stop and assault the women.
The allegations came to light on Sept. 24 when a uniformed police officer learned while on duty of the possible criminal conduct. Alvarez was immediately placed on administrative leave and a criminal investigation started.
An investigation was subsequently forwarded to the Yolo County District Attorney's office. A county grand jury was convened and handed down an indictment.
West Sacramento Police Chief Dan Drummond said the "victimization of vulnerable people is despicable, but the fact that these crimes were apparently committed by a police officer under the color of authority is reprehensible."
He said the actions of one person should not reflect upon the "outstanding performance and integrity" of the men and women of the department.
"I am proud of the way our officers carried out their duties in this investigation and every day in the protection of the community," Drummond was quoted as saying.
Sacramento Police Department was asked to aid the West Sacramento Police Department in the investigation.
Anyone with information related to the case is asked to call the West Sacramento Police Department at (916) 617-4775.