PHOENIX — Angry about the federal government sending from Texas to Arizona immigrants who are in the country illegally, Arizona officials say they are rushing federal supplies to a makeshift holding center in the southern part of the state that’s housing hundreds of migrant children and is running low on the basics.

Gov. Jan Brewer’s spokesman, Andrew Wilder, said Friday that conditions at the holding center are so dire that federal officials have asked the state to immediately ship the medical supplies to the center in Nogales.

A Homeland Security Department official told The Associated Press that about 700 children were sleeping on plastic cots Friday and about 2,000 mattresses have been ordered, and portable toilets and showers have been brought to the holding center — a warehouse that has not been used for detention in years.

The official, who spoke on condition of anonymity because there was no authorization to discuss the matter publicly, said the Nogales holding center opened for children because the Department of Health and Human Services had nowhere to turn.

“They became so overwhelmed and haven’t kept up with planning,” the official said.

U.S. Immigrations and Customs Enforcement has said the immigrants were mostly families from Central America fleeing extreme poverty and violence.

The Homeland Security official said the number of children at the warehouse was expected to double to around 1,400. The warehouse has a capacity of about 1,500.

The station began housing children flown from South Texas last Saturday. About 400 were scheduled to arrive Friday but, due to mechanical issues with the planes, only about 60 came, the Homeland Security official said. Saturday’s flights were canceled, also due to mechanical problems. There are flights scheduled through mid-June.

Federal authorities plan to use the Nogales facility as a way station, where the children will be vaccinated and checked medically. They will then be sent to facilities being set up in Ventura, California, San Antonio, Texas, and Fort Sill, Oklahoma.

The Homeland Security official said that the children would be moved out of the Nogales site as soon as Health and Human Services finds places for them. But the official said: “As quickly as we move them out, we get more. We believe this is just a start.”