Two men and two women were arrested Friday on suspicion of prostitution and pimping, according to the San Mateo County Sheriff's Office.
Jin Deng, 31, and Jin Zhen, 26, both of San Francisco, are accused of pimping, sheriff's officials said. Wenyan Ma, 33, of San Gabriel, and Liuyng Zhang, 50, of Los Angeles, are suspected of committing acts of prostitution.
Law enforcement officials from the San Mateo County sheriff's office, and Redwood City and San Bruno police departments investigated the suspects for a month, according to a statement.
They then served a search and arrest warrant at a house on the 1100 block of Herman Street in San Bruno around 2 p.m. Friday.
It remains unknown what officials found during their investigation and what led to the arrests. It is also unclear how long the business was in operation.
Neighbor Gloria Mendoza was taken aback to learn about about the month-long investigation and arrests.
"I'm surprised for this neighborhood being pretty quiet," she said.
The suspects have been booked into the Maguire Correctional Facility in Redwood City. An investigation is ongoing.
People with information about this case are asked to call the sheriff's office at 650-363-4911. Anonymous tips can be left at 1-800-547-2700.