OAKLAND (CBS SF) — State liquor control agents raided an Oakland karaoke bar early Friday, culminating a three-month investigation that led to the arrest of four suspects on drug and prostitution charges.

The California Department of Alcoholic Beverage Control said the raid and the arrests targeted the Music Café located at 251 Ninth Street.

READ MORE: UPDATE: Lockdown Of Hercules Neighborhood Lockdown Due To Police Activity Lifted

A plate with a powdered ketamine and a straw, which allegedly was being sold at Music Café in Oakland’s Chinatown. (California ABC)

ABC investigators said citizen complaints alleging illegal drug activity, sales to minors and loud music triggered the undercover surveillance. Agents were able to purchase illegal drugs from club employees during the operation including cocaine, ecstasy and ketamine. They also were approached by alleged prostitutes and discovered that alcohol sales were taking place after 2 a.m.

READ MORE: Homeless Encampment On BART Property In Concord Evicted

Authorities said 29-year-old Charlie Phuc Ngo, of Sacramento, was being held for felony sales of narcotics, felony conspiracy and maintaining a house of prostitution.

Jinghan Liu, a 27-year-old from Hayward, was arrested for felony sales of narcotics and felony pimping and pandering. Ying Liu, 41, of Oakland, was arrested for felony sales of narcotics and 23-year-old Oakland resident Wei Na Hu was cited and released on a misdemeanor prostitution charge.

MORE NEWS: Suspect in 1978 Marissa Harvey Sexual Assault and Murder Cold Case Due in Court

In addition to the arrests, agents also confiscated cash and narcotics found on the premises.