NOGALES, Ariz. — Chanting, “Undocumented, unafraid,” three young immigrants brought to the United States illegally as children staged an unorthodox — and risky — demonstration at the U.S.-Mexico border to protest U.S. deportation policies and call for immigration reform.

The three traveled to Mexico in recent weeks and on Monday walked up to the border crossing here and asked to be let into the United States. By early Monday afternoon, they were being interviewed by immigration authorities. It was unclear how long the interviews would last or how authorities would respond.

The action was organized by the National Immigrant Youth Alliance, an activist group, and the immigrants were accompanied by an attorney. They planned to ask for humanitarian parole, which would allow them entry into the country and, failing that, asylum.

The three — Lizbeth Mateo, Lulu Martinez and Marco Saavedra — were joined by four other young immigrants who had gone south of the border not to make a political statement but because living conditions in the United States had compelled them to return to Mexico. A fifth woman who joined the group had been deported from Kansas.

Early Monday, the eight-person group gathered at a restaurant in Nogales, Mexico, and prepared to present themselves to U.S. immigration authorities. “I’m just really excited that the day is finally here,” Martinez said as she signed pages and pages of documents for her humanitarian parole application.

Martinez, 24, attends the University of Illinois in Chicago. “We’re ready to go back home,” she said.

Members of faith groups advocating immigration reform accompanied the immigrants. Before they left the restaurant for the Morley Port of Entry, someone said a prayer: “We pray that you will open the gates, just like you did with the Red Sea.”

“We’re just excited. All our preparing for three years has made this possible,” Saavedra said, referring to other acts of civil disobedience he and other immigrants have staged. Saavedra, 23, was brought to the United States 20 years ago. He graduated from Kenyon College and lives in New York.

Then they were off, dressed in graduation caps and gowns, walking through the streets of the Mexican city. They were later joined by a ninth young immigrant who had self-deported some time ago. She had heard of the demonstration and joined at the last minute.

Word of the demonstration spread and other young immigrants who had self-deported began to present themselves at the border. By early Monday afternoon, an additional 30 immigrants had arrived at the border.

Mateo, 29, a graduate of Cal State Northridge, plans to attend Santa Clara Law School. She paid her tuition Sunday. On Monday morning she tapped out a note to the law school, which starts classes in August.

“I’m letting them know I may not make it in time,” Mateo said.

Meanwhile, on the U.S. side of the border, immigration reform advocates were chanting, “Si se puede” — yes we can. The immigrants' attorney sent a text saying the chants could be heard inside the building where the young immigrants were being interviewed.

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cindy.carcamo@latimes.com

Twitter: @thecindycarcamo