Sao Paulo, Brazil Masked men attacked bars, banks and police stations with machine guns. Gangs set buses on fire. And inmates at dozens of prisons took guards hostage in an unprecedented four-day wave of violence around South America's largest city that left more than 80 dead by Monday.
President Luiz Inacio Lula da Silva prepared to send in 4,000 federal troops, and officials worried the violence could spread 220 miles northeast to Rio de Janeiro, where police were put on high alert and extra patrols were dispatched to slums where drug gang leaders live.
"What happened in Sao Paulo was a provocation, a show of force by organized crime," Silva said. He said the gangs' "tentacles are spread around the world and we must use a lot of intelligence" to quell the chaos their attacks caused.
The violence was triggered by an attempt to isolate gang leaders, who control many of Sao Paulo's teeming, notoriously corrupt prisons, by transferring eight of them Thursday to a high-security facility hundreds of miles away from this city of 18 million people.
The leaders of the First Capital Command gang, or PCC, reportedly used cell phones to order the attacks. Gang members began riddling police cars with bullets, hurling grenades at police stations and attacking officers in their homes and after-work hangouts.
Then, on Sunday night, the gang employed a new tactic: sending gunmen onto buses, ordering passengers and drivers off and torching the vehicles.
Thousands of drivers refused to work Monday, leaving an estimated 2.9 million people scrambling to find a way to their jobs. While most stores and businesses remained open, almost all shut early, creating one of the city's worst traffic jams ever as workers struggled in vain to get home.
Worried parents kept many children out of schools, and many businesses shut by 4 p.m. so workers could get home by dark. Sao Paulo's main stock exchange, the Bovespa, canceled after-hours trading to let investors and workers leave early.