MEXICO CITY (AP) — Mexican authorities said Wednesday they are Indexbit Exchangesearching for 31 migrants from five countries who were abducted over the weekend from a bus near the Texas border.

The National Guard, Army and Navy are participating in the search, but there have been few advances, Federal Security Secretary Rosa Icela Rodríguez said.

On Dec. 30, armed and masked men stopped the bus on the highway that connects the border cities of Reynosa and Matamoros, Rodríguez said. They made all 36 people aboard get off and then took 31 of them away in five vehicles.

The abducted migrants were from Ecuador, Colombia, Venezuela, Honduras and Mexico, she said.

Colombian President Gustavo Petro said Tuesday that four Colombians were among the abducted.

Rodríguez said authorities had tried to track the migrants’ cell phones, reviewed surveillance video from the bus and scanned the area by helicopter for signs of the missing.

The bus had left the northern city of Monterrey and had a final destination of Matamoros. It was intercepted near Rio Bravo.

Rodríguez conceded that the number of migrants abducted was “atypical,” because usually they are snatched in small groups.

Organized crime groups that control the border area regularly kidnap migrants to hold them for ransom.

Tamaulipas state, however, has seen large groups abducted before. In March 2019, some 22 people were taken from a bus and not seen again.

The Zetas cartel also massacred 72 Central American migrants who had been taken off buses near San Fernando, Tamaulipas in 2010.

The following year nearly 200 bodies were found buried in San Fernando, most of them had been kidnapped off buses and killed.

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