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(CNN) —  

A massive caravan of migrants trekking through Mexico is still more than 1,000 miles from the US border, but already other groups are following in their footsteps.

US officials have been keeping their eyes on a caravan that’s forming in El Salvador, a Department of Homeland Security official told CNN on Tuesday. And another migrant caravan of around 2,000 people entered Guatemala from Honduras and is expected to reach Guatemala City on Wednesday.

US-bound migrant caravans are not uncommon, as Central Americans desperate to escape violence and poverty band together for safety on the road. Some advocates also use the mass movements to help draw attention to political causes.

But the formation of new caravans in Central America comes as political pressure mounts over a convoy of thousands of people now transiting Mexico, en route from Honduras to the United States. That caravan has drawn the ire of President Donald Trump, who in an apparent fear campaign aimed at boosting turnout in the November 6 midterm elections, has blamed Democrats, without evidence, for pushing for overrun borders.

Preparing for their arrival

In the Mexican municipality of Suchiate, which borders Guatemala, officials say they’re preparing for more migrants to pass through.

The caravan of around 2,000 people that’s crossing through Guatemala is expected to reach Mexico in the coming days, said Sergio Seis Cabrera, director of attention for migrants and refugees in Suchiate.

The Rev. Mauro Verzeletti, a priest who runs a shelter for migrants in Guatemala’s capital, said the facility has tended to 11,500 migrants in the last 10 days. The majority are Honduran and want to reach the United States, he said.

He described the situation as a humanitarian crisis of unprecedented proportions.

Organizing on WhatsApp

More than 500 people are using four groups in the mobile messaging service WhatsApp to organize a caravan in El Salvador that matches the description of the one the Trump administration is monitoring, CNN has learned.

The migrants in that group plan to leave at 9 a.m. on October 31, from El Salvador’s capital, San Salvador. NBC first reported the DHS tracking and the group’s expected departure point.

One WhatsApp group’s organizer did not want to be identified by name because of potential security risks and reprisals, telling CNN there’s a lot of misinformation about the effort on local Salvadoran news.

People posting about the caravan in WhatsApp seemed energetic and optimistic in their discussions.

The description section in one messaging group reads, “What should I have to wear?” It suggests light luggage with two pairs of comfortable pants, three shirts, three pairs of tennis shoes, a sweater, medicine and, if possible, money, it states.

It also advises people to bring official documents: for adults, a national ID card, and for minors, a passport and birth certificate.

“Don’t be afraid,” an unidentified person who sent around an extended packing list told one group. “These caravans are being monitored by the entire world. Once you reach the US-Mexico border, if you don’t force your way through no one will hurt you. Only God knows what will happen though.”

CNN en Español’s Michelle Mendoza contributed to this report.