A large group of Central Americans is continuing toward Mexico City from the south in an effort to reach the United States.
"We absolutely see people from the Middle East, from southeast Asia, from other parts of the world - not just from Central America", Nielsen told Fox News.
"Canada", said two Hondurans, Marel Santos, 18, and Alexander Chavez, 19, of their intended destination, citing Trump's angry response to the caravan.
"People help more in Chiapas and Oaxaca, " Leyva said, referring to the southern Mexican states the group had already traversed and where pickup trucks frequently stopped to offer rides.
The caravan - which has become a key talking point for President Trump in the final lead-up to Tuesday's midterm elections - is expected to stay in the stadium for a few days. "They're even taking our fearless troops away from their families for a political stunt at the border, and our men and women deserve better than that".
The majority of the migrant caravan has arrived in the Mexican capital, with many still planning to walk hundreds of miles to the USA border.
"The Republicans are very anti-immigrant, the majority of them".
Mexican authorities estimate it now has about 5,000 people, some 500 of whom are still making their way across central and eastern Mexico to rejoin the main group. A third group of about the same size entered the country on Friday.
The caravan has incurred Trump's wrath ahead of Tuesday's US congressional elections.More news: Ariana Grande's Full Performance of 'Thank U, Next' Is Here
Rina Valenzuela wore one of the yellow bracelets as she sat attentively listening to aid workers from the nonprofit Institute for Women in Migration explain the difficulties of applying for and securing asylum in the U.S. Valenzuela, who is from El Salvador, decided she's better off applying for refuge in Mexico. "They're definitely organized or financed".
Two other caravans with around 2,000 migrants each are now making their way across southern Mexico.
"They don't want to get into a confrontation with a child, [or] women, and so they're nearly being used as barriers at the front of some of these caravans", Nielsen explained.
The caravan is trying to make 116 miles, a record for them, considering the first day of walking in Mexico they traveled just 20 miles.
The caravan had spread out in recent days, with many participants advancing at a faster pace. A caravan last spring opted for a much longer route to Tijuana in the far northwest, across from San Diego.
Others, however, had messages for the American president on voting day. The office said earlier this year that a wave of disappearances took place in Tamaulipas state and urged Mexican officials to act to prevent further crimes.
"Humire said the number of non-Central American migrants may be as high as 232 in Guatamala alone - based on new information he received from that country's intelligence service", Herridge pointed out.
"We're not criminals. We're hard-working people", said 25-year-old Honduran Eber Josue.
Many went to medical tents to get treatment for blistered and aching feet, illness and other maladies.More news: Cheryl Jessie Ware Podcast: Singer speaks out on Liam Payne's dating
"We have seen individuals", Humire stressed.
Trump has alleged the caravan includes members of the violent street gang MS-13.
And the cost to American taxpayers could still rise.
Mexico's Interior Ministry estimated over the weekend that there are more than 5,000 migrants in total now moving through Mexico.
But the migrants reportedly have just one clear motive - to reach the USA - not merely to find a safe place to live that can support them.
The commander-in-chief is not taking chances with the latest caravan invasion strewn with criminals and likely jihadists - even though the leftist media hub CNBC.com claimed the Pentagon does not consider the caravans as a risk to the US ... despite accounts of militant migrants attacking law enforcement in Mexico. Helpfully, AP once again inadvertently proved that the migrants aren't running for their lives, as their leftist supporters in the United States insist, but instead are running for jobs.
But the caravan's numbers are dwindling, news and official reports say, as even a third caravan crossed into Mexico on Friday, likely with the same goal in mind: Crash the US border and tell (perhaps phony) tales of persecution to get asylum and lawsuits filed by anti-American leftists.
"The first caravan grew as large as about 7,000 people, but has reportedly shrunk by almost half as people turn back or quit the journey in Mexico, [while] a second caravan of about 1,000 migrants is also making its way through Mexico", Colen continued. He will send more than 7,000 soldiers to the border states of Texas, Arizona and California.More news: FA appeals against decision to clear José Mourinho over touchline language