NOGALES, Arizona (AP) — U.S. Homeland Security Secretary Jeh Johnson warned Central American families on Wednesday that "there is no free pass" in the immigration system, after touring an Arizona facility holding hundreds of children apprehended at the border with Mexico in recent weeks.

Arizona Gov. Jan Brewer, who has long been a critic of the Obama administration's immigration policies, toured the converted warehouse in Nogales with Johnson and declared that the government is not doing its job in stopping the overwhelming surge in children illegally migrating to the U.S.

Thousands of Central American families and unaccompanied children have been coming to the U.S. in recent months as they flee violence, murders and extortion from criminal gangs in Guatemala, El Salvador and Honduras. Many think they will receive leniency from U.S. authorities.

"I want to continue to emphasize to all those who are listening, including the parents of kids, parents that may be considering sending their kid from Central America, that this journey is a dangerous one, and at the end of it there is no free pass, there is no 'permisos' for your children to come to the United States," Johnson said.

About 900 children are being held in the Nogales facility, where they are processed and turned over to the Department of Health and Human Services while undergoing removal proceedings. They are often reunited with their families in the U.S. before their immigration court cases are over.

Johnson says the kids have adequate care. But he has kept quiet about how many children have been sent to Arizona, how many have been released and how many have reported back to immigration officials as required.

Border Patrol agents have apprehended more than 52,000 immigrant children crossing the border alone since the start of the budget year last October. That included 9,000 in May. Most have been caught in the Rio Grande Valley of Texas, which has run out of space and resources to process the children.

The surge in crossings has prompted the Department of Homeland Security to fly many kids to Arizona for processing. The department is also using military bases in Texas, California and Oklahoma to house the children before they are placed with a parent or relative. Other facilities in New Mexico and Arizona are being set up to house immigrants.

Immigration officials have also released a large number of women with children who crossed the border illegally into Texas, dropping them off at bus stations in Phoenix and Tucson with the expectation that they will report back within 15 days. Officials have not said how many have reported back.

Doris Suyapa Leyba Juarez is one of the thousands of people who have come to the U.S. from Central America in the recent surge.

As she sat on the ground in a dark corner of a Phoenix bus station last month holding a 2-year-old girl, the mother of five said she wanted to come to the U.S. to give her kids the educational opportunities she didn't have in Honduras.

"I just want my kids to study. I can't read or write," she said.