Hours before dawn, Julio Arrivillaga and Catalina Pérez Molina boarded a bus with other residents in the center of the humble village of Santo Domingo Los Ocotes in Guatemala for what should have been an hour-long ride to Guatemala’s capital.

The bus carrying mainly commuters and students plunged into a ravine outside Guatemala City.

At least 51 people were killed as a bus plunged into a ravine early Monday in Guatemala City, officials said. At least 20 more were seriously injured, they said. City officials said the incident occurred when the bus veered off a highway and went into a ravine.