MEXICO CITY — Nineteen people died and six others were injured when a bus crashed on a highway in Mexico’s central state of Zacatecas on Saturday, local authorities said.

The accident occurred in the early morning hours when the bus carrying the victims collided with the back of a tractor-trailer carrying corn, which had come loose.

Zacatecas Governor David Monreal earlier on Saturday had initially reported a preliminary death toll of 24 people, but the state attorney general’s office…