(CNN) Maximo, an asylum seeker, fled his native Honduras with his son to seek a new life in the United States.

But while waiting for their cases to be heard he says they have practically become prisoners in a shelter for migrants in the Mexican border town of Nuevo Laredo, where cartels prey on migrants who venture out into the streets. He and his son were nearly kidnapped, he says.

"We are alone and only God's hand has kept us safe from the constant danger that surges in this country," he wrote in a letter. "We don't intend to cause any harm to the United States. We would just like a safe place [to wait] for a response from the government."

Maximo is among tens of thousands of asylum seekers who under Trump administration policy must wait in Mexico for their US immigration proceedings.

He and nearly two dozen other migrants at the border responded to a request from Denise LaRock, an American nun who advocates for immigrants, to write letters explaining their hazardous situation. LaRock told the migrants she would share the letters with journalists to bring attention to the dangers they face.

Read More