More than 130 people were arrested last week in the Bay Area during "Operation Strikeout," which targeted pimps, prostitutes and their customers during Major League Baseball's All-Star game in San Francisco.

Oakland police spokesman Roland Holmgren said during a news conference Monday that the sting was employed from July 6-12 because prostitutes tend to show up in areas that are hosting high-profile events, such as All-Star games.

More than 10 agencies teamed up during in the sting -- which included officials conducting undercover operations, posing as prostitutes and engaging in Internet rings. The operation resulted in 131 arrests, including 46 in San Francisco and 40 in Oakland.

Among those arrested were four girls under the age of 18. One of the minors arrested by the South San Francisco police department brought her 8-month-old baby with her to work.

Nola Brantley, the director of Oakland's Sexually and Commercially Exploited Youth Program, said she has seen in an increase in the number of underage prostitutes in recent years, and that these girls tend to work for violent pimps.