TECUN UMAN, Guatemala (AP) — Waving Honduran flags and carrying umbrellas to protect against the sun, thousands of migrants massed along Guatemala's muddy Suchiate River crossing into Mexico on Friday, demanding to be let in despite U.S. President Donald Trump's threats of retaliation.

"One way or another, we will pass," the migrants chanted as they moved toward the bridge that connects the two countries as a disorganized crowd of women, men and children. They got as far as a closed metal gate where two military jeeps were parked and Guatemalan police in riot gear looked on silently.

"We are not smugglers, we are immigrants!" the crowd shouted as they approached the yellow metal gate. Some climbed atop the gate and the U.S.-donated jeeps as they clamored to be allowed to pass.

Dozens of Mexican federal police officers were on the bridge, backed up by hundreds more officers deployed behind it, and Mexico's ambassador to Guatemala said his country was enforcing what he called a policy of orderly entry in the face of the thousands trying to cross.

"It is an illegal activity," said Ambassador Luis Manuel Lopez Moreno, adding that more than 100 migrants had been allowed to cross the bridge to apply for refugee status, including some who were from the caravan and others who were not.

Meanwhile, the rafts that normally ferry throngs of people across the river were carrying mostly merchandise and the raft operators said they had been warned by Mexican authorities not to carry people.

Jose Porfirio Orellana, a 47-year-old acorn and bean farmer from Yoro province in Honduras, said he hopes to reach the United States due to woeful economic conditions in his country.

"There is nothing there," Orellana said.

The first members of the 3,000-strong caravan began arriving in the Guatemalan border town of Tecun Uman on buses and trucks early Thursday, but the bulk of the group sloshed into town on foot in a downpour late in the afternoon and into the evening. Before dawn Friday, the migrants decided to wait a few more hours for stragglers to arrive.

Some planned to walk toward Mexican territory in a formation that put the men along the edges and the women and children in the center. Others prepared to cross the river in rafts, the traditional way migrants enter.

As the sun rose, a military helicopter flew along the Mexican side of the river foreshadowing the difficulties they could face. At the same time, several busloads of Mexican federal police in riot gear deployed at the border crossing in Ciudad Hidalgo.

Jonathan Guzman, who joined the mass procession caravan en route, said he dreams of finding a construction job in Los Angeles. "It's the third time that I'm trying to cross," the 22-year-old Salvadoran said.

Mexican Foreign Relations Secretary Luis Videgaray said those with passports and valid visas would be let in immediately, though he acknowledged that "we anticipate those are the minority."

Those who want to apply for refuge in Mexico will be welcome to do so "if they have a vulnerable situation in their country of origin," Videgaray said in an interview with the Televisa network.

Any who decide to cross illegally and are caught will be detained and deported, the Mexican government has said.

Trump has made it clear to Mexico that he is monitoring its response. Early Thursday, he threatened to close the U.S. border if Mexico let the migrants advance. Later, he retweeted a video of Mexican federal police arriving at the Guatemalan border and wrote: "Thank you Mexico, we look forward to working with you!"

In April, Mexican immigration officials had some success in dispersing a smaller caravan by processing many who decided to seek refugee status in Mexico, but some did continue on to the U.S. border.

Asked in the Televisa interview whether Mexico was doing Trump's "dirty work," Videgaray said Mexico "defines its migration policy in a sovereign manner" and the country's priority is to protect the migrants and ensure their human rights.

He did not seem concerned about Trump's threat to close the U.S.-Mexico border, saying the threat should be viewed in light of the hotly contested midterm elections in the United States, in which Trump has made border security a major campaign issue.

The foreign secretary noted that 1 million people transit the border legally every day, and about $1 million in commerce crosses every minute.

"Before taking decisions of that kind," Videgaray said, "there would be many people in the United States ... who would consider the consequences."