HOUSTON >> Militia groups and far-right activists are raising money and announcing plans to head to the Mexican border to help stop the caravan of Central Americans, echoing President Donald Trump’s attacks on the migrants making their way toward the U.S.

Exactly how many militia members will turn out is unclear, and as of Friday, the caravan of about 4,000 people was still some 1,000 miles and weeks away from reaching this country.

But the prospect of armed civilians at the border — and the escalating political rhetoric over immigration — have fueled fears of vigilantism at a time when tensions are already running high because of the mail bomb attacks against some of Trump’s critics.

The U.S. Border Patrol this week warned local landowners in Texas that it expects “possible armed civilians” to come onto their property because of the caravan.

Three activists told The Associated Press that they were going to the border or organizing others, and groups on Facebook have posted dire warnings about the caravan. One said it was “imperative that we have boots on the ground.” Another wrote: “WAR! SECURE THE BORDER NOW!”

The militia members said they plan to bring guns and equipment such as bulletproof vests and lend a hand to the Border Patrol to protect against people unlawfully entering the country.

“They’re just laughing in our face,” said Shannon McGauley, president of the Texas Minutemen. “It’s a free-for-all in America.”

McGauley said he already has members at three points of the state’s border with Mexico and expects to add 25 to 100 more people in the coming days.

Border watch groups and militias have been patrolling the 2,000-mile southern boundary off and on for more than a decade. Typically, the groups watch for people illegally crossing into the U.S. When they spot crossers, they contact the Border Patrol.

Their presence has led to conflict in some cases. A militia member killed two people in 2009 during an invasion of what she thought was a drug house near the border in Arivaca, Arizona.

Residents in that same city have been posting signs in recent weeks warning that militia members are not welcome.

The migrants’ northward trek has led to an election-season furor in the U.S., with Trump calling for the Army to be sent to the border and a Pentagon official saying the administration will dispatch 800 or more active-duty troops.

Border crossings, while rising this year, are still far below the numbers in previous decades. But Harel Shapira, a University of Texas professor who was embedded with an Arizona militia from 2005 to 2008, said that what’s driving militia groups is the way some politicians have more recently defined immigrants as “existential threats to a particular way of life.”

Monica Marin, an Oregon resident, said she has raised about $4,000 online to help militias buy supplies. She argued that members of the caravan are dangerous, echoing Trump’s claim that “unknown Middle Easterners” are mixed in with the crowd. There is no evidence to support those claims.

“I see young, fighting-age men who do not look like they’re starving. They look like they’re ready to fight,” Marin said. At the same time, she said: “We’re trained. We’re not hotheads. We’re not out there to shoot people.”

Marianna Trevino Wright, a South Texas resident who is director of the nonprofit National Butterfly Center, said she is more fearful of the militias than the caravan.

“We go about our business here every day in a peaceful manner,” Wright said. “The idea that we could be invaded not by illegal immigrants but by militia groups … is regrettable, and it will end badly.”