MEXICO CITY—Mexican soldiers, armed police, and migration officials blocked hundreds of migrants after they crossed the border from Guatemala in a caravan into southern Mexico on June 5, and detained dozens of them, a witness from a migrant aid group and an official said.

A migrant argues with a federal police officer during a joint operation by the Mexican government to stop a caravan of Central American migrants on their way to the United States, at Metapa de Dominguez, in Chiapas state, Mexico, on June 5, 2019. Jose Torres/Reuters
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