MEXICO CITY (AP) — Mexican immigration authorities said Sunday they found the bodies of three apparent migrants who drowned trying to cross the Rio Grande, the border river with Texas also known as the Rio Bravo.

The National Immigration Institute said no identification was found on two of the bodies, but a third bore documents indicating he was from Nicaragua.

Officers from the institute’s migrant protection team also found three migrants alive but unable to continue crossing the river due to cold water temperatures and strong currents.

The woman, a 2-year-old girl and an 8-year-old boy, all from Honduras, were rescued with an airboat and taken to a shelter in the border city of Piedras Negras.

It was the latest in a series of migrant deaths in Mexico that some activists attribute to heightened security that has led some migrants to use riskier routes to reach and cross the U.S. border.

Earlier this week, a bus crash in northern Mexico killed seven migrants and injured 24. One of those killed was a pregnant woman and two of the injured were minors.

No nationalities were immediately available for the seven dead, but of those who survived, 11 were from El Salvador, seven from Honduras and four from Cuba. Also injured were one Panamanian and one Mexican citizen.

The bus plunged through a guardrail and down an embankment in the northern state of San Luis Potosi on Wednesday.

Immigrant traffickers frequently cram migrants aboard freight trucks and buses to traverse Mexico on their way to the United States.

On Tuesday, authorities in the Gulf coast state of Veracruz said six migrants drowned off Mexico’s Gulf coast and one was missing. Apparently, all were from Honduras. Smugglers sometimes take migrants in open boats across the Gulf to avoid highway immigration checkpoints.

Four migrants, also Hondurans, were pulled alive from the ocean by rescuers after their 25-foot open boat apparently capsized off the coast.

In another incident, immigration officials said last week that a migrant father and his 7-year-old son were found dead in the Suchiate River, which marks the border between Mexico and Guatemala. Officials said the 36-year-old man and his son were from El Salvador.

Migrants frequently wade, swim or take rafts and boats to cross border rivers to reach the United States.

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