Homeland Security Secretary Kirstjen Nielsen said Friday that the death of a seven-year-old migrant girl last week shows just how dangerous it can be to cross into the U.S. illegally.

"It's heart-wrenching is what it is, and my heart goes out to the family and all of DHS," Nielsen said on Fox News.

"This is just a very sad example of the dangers of this journey," she added. "This family chose to cross illegally."

She said dozens of Guatemalan migrants were caught in the New Mexico desert, about 90 miles away from where they could be processed. DHS tried to help her upon discovering she had a body temperature of 105.7 degrees and was having seizures.

They took her by helicopter to an El Paso hospital, where she went into cardiac arrest and died a day later.

"We gave immediate care," Nielsen said. "We'll continue to look into the situation, but again, I cannot stress how dangerous this journey is when migrants choose to come here illegally."