Police in Mexico City are holding 187 mostly minors in what appears to have been one of Mexico's first instances of flash mob violence.
While the use of social networks is growing in Mexico, the country had largely escaped the kind of rapidly formed, fast-moving youth mobs seen in Europe and the United States.
City police chief Manuel Mondragon said Monday that two young men had called on other people to gather for a concert of reggaeton music at a bar. Hundreds more showed up than could fit.
Mondragon says angry youths who couldn't get in to the Sunday concert went on a rampage at subway stations, damaging turnstiles and streetlamps, robbing people and tossing fireworks. Police say 39 people were released Monday because of lack of evidence.