In one of the largest outbursts of passenger fury over poor service in years, mostly working-class commuters rioted at the Constitucion Plaza station in Buenos Aires after a train breakdown threw Tuesday's departures into chaos. Rioters set fires, destroyed ticket booths and looted shops. About 100 police fought back with tear gas and arrested 16 rioters. Another 21 people were injured. Passengers on commuter rail lines, privatized in the 1990s under then-President Carlos Menem, for years have complained the new operators are failing to provide timely service on crowded routes. On Wednesday, President Nestor Kirchner threatened to crack down on those who do not modernize lines.