MILLBRAE >> A 47-year-old masseur from Hayward was arrested on suspicion of sexually assaulting a victim during a massage therapy session last month. Authorities believe there may be more victims and have urged them to come forward.

According to the San Mateo County Sheriff’s Office, deputies were notified of a sexual assault that occurred during a massage therapy session on Dec. 22 at a business in the 900 block of Broadway in Millbrae. A woman reported “unwanted, inappropriate, and sexual touching” by a male massage therapist, police said.

Officials said the victim was provided resources before the sheriff’s office began its investigation.

They identified 47-year-old Guosheng Chen as a suspect and Tuesday, a $400,000 arrest warrant was obtained to detain him. Chen was taken into custody Thursday with assistance from the Hayward Police Department. He was booked into the Maguire Correctional Facility in Redwood City on suspicion of oral copulation, sexual penetration and sexual battery involving an unconscious person.

Sheriff’s officials said Chen had previously worked as a massage therapist throughout the state, including in Alameda County, Contra Costa County, San Diego County and San Mateo County.

Investigators believe there may be additional unidentified victims and encouraged anyone with information to come forward.

Anyone who recognizes Chen or has further information about this or any other unreported crime can contact Detective Pitts at 650-363-4060 or by email at npitts@ smcgov.org.