Carlos Miguel Palo had barely been back on the job for a week when the first terrifying call came in. It was August 2007 and Palo, a short, gregarious man in his early thirties (whose name has been changed to protect his identity), was driving his bus through the humid streets of Guatemala City. It had been a long time since he had been behind the wheel and he was happy to be there. Dressed in his usual wardrobe of brightly colored polo shirts, he joked with the other drivers and passengers as he went along his route.

Palo’s bus was part of the fleet of almost 10,000 privately owned urbano passenger buses that provides Guatemala City’s working class with cheap transportation. Every day, more than a million people—or a third of the city—use the buses, which are heavily subsidized by the government to keep them affordable. On a good day, Palo’s bus was packed throughout his entire 14-hour shift: students, housewives, day laborers, street vendors with woven shawls or baskets of cheap sunglasses.

Like most of the city’s buses, Palo’s was a Blue Bird, the ubiquitous American school bus; it had spent its early life in some far-off school district before being sold at auction and driven to Guatemala City. The bus system was good business: After years of working in the industry as a route supervisor, Palo had bought four buses as an investment and joined a cooperative named Transportes Libertad (the name of which has been changed to protect the owners’ identities). Until recently, he had rented this bus out to another driver for 300 quetzales a day, around $40. The driver was able to keep whatever fares he collected on top of that, which could be up to five times as much. But Palo had recently been laid off from another job at a trucking company. He was restless sitting at home, and with two children to support, he thought the money would be better off going to him.

On this particular day, Palo was winding through the city, heading from the working-class neighborhoods of Zone 6 to the downtown Terminal, a giant open-air bus station with pitted asphalt that serves as the bus system’s hub. The streets he passed had a fortified look—stores had bars on their windows and were flanked by private guards with pump-action shotguns. In the wake of the country’s 36-year civil war, the military and police had ceased to be effective forces; there were now far more private security guards than uniformed cops. Palo had no armed guard, but he wasn’t worried. There had been only occasional instances of petty crime against drivers, mostly robberies. Then his cell phone rang. It was the director of Libertad. Return immediately to the office, he told Palo. We have an emergency.

Palo rushed back to Libertad’s headquarters, a canary yellow row house in a quiet neighborhood in Zone 2, a little north of downtown. Inside, he found the director and the other bus owners gathered around a cheap, black disposable cell phone. A young man had dropped it off at the office, demanded that it be given to the directors, then left.