MEXICO CITY -- The migrants were kidnapped in broad daylight.
At least 19 men believed to be from Central America were traveling on a bus in northern Mexico last week when masked gunmen stormed aboard, forced the migrants onto pickup trucks, then sped away, Mexican officials said.
The violent incident on March 7, which took place just miles from the U.S. border, was not unique. A group of 25 migrants was pulled off another bus under similar circumstances in February, a top Mexican human rights officials said this week. The migrants' whereabouts are unknown.
The two cases highlight the risks faced by Central American migrants in Mexico, where criminal groups have diversified well beyond drug trafficking and now help smuggle migrants north and sometimes extort or kidnap them for ransom.
Conditions for migrants in Mexico have been under added scrutiny in recent months since U.S. officials began sending some Central Americans who have applied for political asylum to Mexico to await rulings in their cases.
Since January, more than 200 migrants have been returned to the border city of Tijuana under the so-called Remain in Mexico program, which U.S. officials say they plan to expand to other parts of the border soon.
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Northern Mexico, and Tamaulipas in particular, is known for being dangerous territory for migrants.
In 2010, 72 men and women seeking to reach the U.S. were kidnapped in Tamaulipas and then shot to death at a ranch near the city of San Fernando. Mexican officials blamed the massacre on the Zetas, a powerful criminal group, saying the kidnappers killed the migrants after they refused to join the gang.
The migrants kidnapped last week were traveling on a bus route that traversed the roughly 90 miles from San Fernando to the border city of Reynosa, officials said. Mexican officials have offered different estimates of the number of victims -- ranging from 19 to 22 -- as well as various theories of possible motives.
Mexican President Andres Manuel Lopez Obrador speculated that the migrants may have staged their own kidnapping as a way to deceive immigration officials.