At least 54 people were killed after a bus veered off a bridge into a ravine in Guatemala City on Monday, according to the country’s National Institute of Forensic Sciences.

The bus collided with other vehicles on a main bridge in Guatemala’s capital before falling into a ravine early Monday morning.

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.