DONAJI, Mexico — A third caravan of migrants — this time from El Salvador — waded over the Suchiate River into Mexico on Friday, bringing another 1,000 to 1,500 people hoping to reach the U.S. border.

The third caravan tried to cross the bridge between Guatemala and Mexico, but Mexican authorities told those traveling in it they would have to show passports and visas and enter in groups of 50 for processing. The Salvadorans expressed misgivings that they would be deported, so they turned around and waded across a shallow stretch of the river to enter Mexico.

Although police were present, they did not try to physically stop the migrants, who later walked along a highway toward the nearest large city, Tapachula.

Mexico is now faced with the unprecedented situation of having three migrant caravans stretched out over 300 miles of highways in the southern states of Chiapas and Oaxaca. The first, largest group of almost 4,000 entered almost two weeks ago and is now in Donaji, Oaxaca.

The second caravan, also of about 1,000 to 1,500 people, is now in Mapastepec, Chiapas.

It remained unclear whether the first caravan will make a turn east to Mexico City, or try to reach the nearest and most dangerous stretch of border, which lies almost directly north. Divisions began to appear about what route to take.

It also remained unclear how many migrants would make it; 20 days of scorching heat, constant walking, chills, rain and illness had taken their toll. Mexico’s Interior Department said Thursday nearly 3,000 of the migrants have applied for refuge in Mexico and hundreds more have returned home. At its peak, the caravan had about 7,000 people.

Honduran migrant Saul Guzman, 48, spent the night under a tin roof in the Oaxaca state town of Matias Romero with his son Dannys, 12, before setting out for the town of Donaji, 30 miles north.

“I have been through a lot,” said Guzman. “I want to spend my time differently, not in poverty.”

In his hometown of Ocotepeque, Honduras, he left behind a coffin, either for his mother, who suffers dementia, “or for me, if I don’t make it,” Guzman said.

The migrants had already made a grueling 40-mile trek from Juchitan, Oaxaca, on Thursday, after they failed to get the bus transportation they had hoped for. But hitching rides allowed them to get to Donaji early, and some headed to a town even further north, Sayula.

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The migrants have not said what route they intend to take, but any trek through the Gulf coast state of Veracruz could take them toward the Texas border. Another large caravan early this year passed through Veracruz but then veered back toward Mexico City and eventually tried to head to Tijuana in the far northwest. Few made it.

Immigration agents and police have been nibbling at the edges of the first two caravans.

A federal official who was not authorized to be quoted by name said 153 migrants in the second caravan were detained Wednesday during highway inspections in Chiapas, a short distance from the Guatemalan border.

There was also pressure on the first caravan. Not only did the hoped-for buses not arrive, but federal police began pulling freight trucks over and forcing migrants off, saying their habit of clinging to the tops or sides of the trucks was dangerous.

At other points along the route, police have forced overloaded pickups to drop off migrants. On previous days, they have ordered passenger vans to stop helping with transportation.

White House press secretary Sarah Huckabee Sanders earlier praised Mexico for stopping the migrants from getting rides.

“Mexico has stepped up in an unprecedented way,” Sanders told Fox News. “They have helped stop a lot of the transportation means of these individuals in these caravans, forcing them walking. They have helped us in new ways to slow this down, to break this up and keep it from moving as aggressively toward the United States.”

But U.S. President Donald Trump ramped up his pre-election focus on the caravan and others behind it, talking of creating a U.S. military force on the border that would outnumber the migrants, many of them women and children.

“As far as the caravan is concerned, our military is out,” Trump said. “We have about 5,800. We’ll go up to anywhere between 10,000 and 15,000 military personnel on top of Border Patrol, ICE and everybody else at the border.”

Similar caravans have occurred regularly over the years and passed largely unnoticed, but Trump has focused on the latest marchers seeking to make border security a hot-button issue in next week’s midterm elections.

Associated Press writer Peter Orsi in Mexico City contributed to this report.