GUATEMALA CITY — At least 55 people were killed in Guatemala on Monday when a bus crashed through a guardrail and plunged into a ravine, authorities said, in one of the worst road accidents in Latin America in years.

An investigation into the crash is ongoing.A bus carrying more than 70 people veered off a highway bridge into a polluted ravine in Guatemala City on Monday, killing at least 51 people, officials said.

A bus carrying 75 people plunged into a ravine in Guatemala City on Monday, killing at least 31 people and leaving others trapped under the wreckage in a river, rescue workers said.