The so-called migrant caravan bound for the U.S. has split into several groups.
A majority of about 4,000 migrants are continuing their journey as a group, trekking along what some in the group have called the "route of death" toward Cardoba, Veracruz, The Associated Press reports.
The roughly 124-mile journey will be the longest walk yet for the group.
The path takes them through the agricultural lands of Veracruz, where hundreds of migrants have disappeared in recent years, likely kidnapped by people looking to gain ransom payments, the news agency reports.
Veracruz authorities earlier this year reported they have found remains of at least 174 people buried in secret, though it is unclear what the bodies' origins are.
Mexican authorities also say about 3,000 immigrants from the first caravan have applied for refuge in Mexico, while hundreds more have turned back.
According to AP, Mexico is facing an unprecedented situation, with three caravans entering the country over 300 miles, traveling up the highway in Chiapas, Oaxaca, and Veracruz.
In total, 6,000 migrants are making their way through the country, heading toward the U.S. border.
President Trump has focused on the caravan as the midterms speed closer.
He said last Wednesday that he may deploy as many as 15,000 troops to the border, where 5,200 U.S. soldiers are already bound.