MEXICO CITY — A 10-year-old Guatemalan girl who was migrating to the United States with her mother died in Mexican government custody on Tuesday night.

Mexico’s immigration agency released information about the girl’s death on Thursday, saying in a statement that before she died she was being treated for “a sore throat.”

It is the first time in recent memory that a migrant child has died in Mexican government custody, and it comes as Mexico’s government appears to be cracking down on migrants transiting through the country en route to the United States. Between January to April, Mexico deported 39,653 migrants.

It came on the same day a 2½-year-old Guatemalan boy died in El Paso several weeks after being apprehended by U.S. immigration authorities He was the fourth migrant child to die since December after being apprehended on the southern border.

The girl and her mother had arrived in the northern Mexican state of Chihuahua when they were “rescued” by Mexican immigration authorities, said an official at the National Migration Institute, who spoke on the condition of anonymity because she was not authorized to speak to the press. 

But Mexican authorities typically use the word “rescued” when describing migrants who are detained and deported. Mexican migration officials would not provide additional information on whether the child and her mother were apprehended or voluntarily agreed to return to Guatemala.

The institute said the mother and child were both examined by medical professionals in Chihuahua and, after being deemed healthy, were sent by bus to Mexico City, a 17-hour drive.

After arriving in Mexico City, the girl was immediately taken to a pediatric hospital with a sore throat. Mexican officials would not say how long afterward she died. In the news release, migration officials called her death “a painful fact.”