Houston — A Texas woman who drove to Mexico to deliver Christmas gifts to a sprawling refugee camp housing people waiting for U.S. court dates said Wednesday she was detained by authorities there for two days.

Anamichelle Castellano said she and another volunteer for her nonprofit group were stopped Monday at a bridge crossing from Brownsville, Texas, to Matamoros, Mexico. She said authorities discovered a small box of ammunition inside the car she was driving, which she said was left inside by her husband.

Mexico has strict laws against entering the country with guns or ammunition. Those laws occasionally ensnare Americans crossing the border.

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Castellano said she spent Monday night sleeping on a couch with her 9-year-old daughter in a government office. She gave a statement Tuesday to someone she believed to be a prosecutor, then was allowed to leave a few hours later. The prosecutor's office in Mexico's Tamaulipas state did not immediately respond to a request for comment Wednesday.

Honduran asylum-seeking child, Elias, 2, plays near the tent where he lives in refugee camp in Matamoros, Mexico on December 7, 2019. VERONICA CARDENAS / REUTERS

Castellano and her husband, Jehu, operate a nonprofit called the Socorro Foundation. They are among the volunteers trying to help thousands of parents and children waiting in Mexican border towns to seek asylum in American immigration courts.

President Trump's administration has prevented many asylum seekers from entering the country or removed them from the U.S. while their cases are still pending under a policy known as "Remain in Mexico."

"Our faith is very strong," said her father, Genaro Lopez, on Wednesday. "God didn't blink. He had a plan."

Castellano said she and a group of volunteers had worked late into the night to wrap presents for children at the Matamoros camp, which consists of hundreds of tents pitched on the land next to the Rio Grande, the river separating the U.S. and Mexico in Texas.

She said she had car trouble early Monday and ended up driving her husband's car. Her husband eventually took hers. They split about 300 gifts between the two.

While her husband drove into Matamoros without incident, an official told Castellano her vehicle would require extra screening. When she was told officers would unwrap all the gifts in her vehicle to check them for anything dangerous, she consented to the officers using an X-ray machine to examine the vehicle.

That scan uncovered a small box of ammunition, which she described as about the size of the palm of a hand. Castellano said she didn't know about the box until the scan and had not intended to take it into Mexico.

She was told conflicting information during the two days about whether she could leave or if she would be imprisoned. She identified officers from at least three different agencies who asked her questions.

Ultimately, she was told that she and the other volunteer could leave if they paid $8,000. The fee was eventually lowered to about $4,000, and her husband paid $3,000.

She was told that she may have to return to see a judge in Reynosa, which she said she would do as soon as a court date was issued.

"I serve refugees," she said. "To tell me that I can't go back and give them their gifts and their needed supplies, I can't risk that."