Mexico launches search for 19 missing migrants The Mexican government says it is launching a formal search for 19 migrants who were pulled from a bus by armed men in the northern border state of Tamaulipas

MEXICO CITY -- The Mexican government said Wednesday it is launching a formal search for 19 migrants who were pulled from a bus last week by armed men in the northern border state of Tamaulipas.

Tamaulipas state police, the army, federal police and prosecutors will participate in the search, according to the National Search Commission for Missing Persons.

Mexico's top security official said Tuesday that in addition to the 19 seized last week, 25 others were kidnapped last month from a different bus, for a total of 44.

The search effort, dubbed "Operation to Find them Alive," refers specifically to the 19 men snatched in the more recent incident. It wasn't clear if a separate effort was underway for the 25, though some Mexican officials have suggested the victims might already be in the United States.

The government hasn't specified the nationalities of the victims, but they are believed to be from Central America.

The kidnappings recall the horrors of 2011, when dozens of passengers were hauled off buses by drug gangs in Tamaulipas, killed and their bodies dumped in mass graves. In 2010, dozens of migrants were also abducted and massacred by the same gang.

For that very reason, most of the migrant caravans that have crossed Mexico in recent months have carefully avoided crossing through Tamaulipas, even though it often represents the shortest route to the U.S. border.

On Tuesday, President Andres Manuel Lopez Obrador said "we are investigating to be sure, because there is a theory that this is a method that is used to get into U.S. territory. It's not that they disappear, but rather that they cross the border that way. We have already had two cases like that."

Officials said there were indications the missing men had hired a smuggler to get them over the border. But it was unclear why the smugglers would have used such an elaborate and violent plan to meet the migrants.

Lopez Obrador is desperate to avoid any repetition of the massacres of 2010 and 2011, saying "that is what we are most worried about."

In the past, drug gangs have often kidnapped migrants to demand ransom payments from their relatives in the United States. But officials said no reports of ransom demands have been received in the most recent cases.