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Pop star Justin Bieber, front, performs during a free open-air concert in Mexico City, Monday, June 11, 2012. (AP Photo/Alexandre Meneghini)

Mexico City packed for Bieber concert

Thousands of "tween" girls jammed a vast square with their parents and screamed in unison throughout teen superstar Justin Bieber's free concert June 11, an event that was expected to draw 200,000 people to the historic center of Mexico's capital.