Article Photos: Sao Paulo could face gang war with truce collapse

A torched commuter bus is surrounded by police tape in a suburb of Sao Paulo, Brazil, Monday, Nov. 12, 2012. Bus burnings were part of a wave of violence that left 31 dead over the weekend in Sao Paulo, according to police. (AP Photo/Andre Penner)

A torched commuter bus is surrounded by police tape in a suburb of Sao Paulo, Brazil, Monday, Nov. 12, 2012. Bus burnings were part of a wave of violence that left 31 dead over the weekend in Sao Paulo, according to police. (AP Photo/Andre Penner)