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.

Dozens of Guatemalan families were in mourning on Monday after an extra-urban bus lost control in northern Guatemala City, plunged down a ravine, and fell into a sewage river, leaving at least 51 dead—many of them workers and students on their way to the capital.