Opposition Democrats in the US have demanded an inquiry after a 16-year-old migrant died at a detention centre on the border with Mexico.
Carlos Gregorio Hernandez Vásquez, who died on Monday, is the fifth child to die after being held since December.
Democratic Texas congressman Joaquin Castro spoke of an “epidemic of death” in the border area.
President Donald Trump has vowed to clamp down on illegal immigration at the southern border.
In February, Mr Trump declared a national emergency to appropriate funds for a border wall.
There has been an increase in migrants trying to cross the frontier this year, and border agents say they are struggling to process the numbers.
What happened to Carlos Gregorio Hernandez Vásquez?
Border agents apprehended the Guatemalan teenager for illegally crossing the border on 13 May and took him to a central processing centre in McAllen, Texas. He was travelling alone.
On 19 May, the 16 year old was diagnosed with flu and given medicine. He was transferred to the Welasco Border Patrol Station, reportedly in order for the illness to be contained.
On Monday, he was found unresponsive. An official cause of death has not been announced.
His brother in New Jersey told broadcaster CBS News of his shock, that Carlos would die in a country where he had come for a better life.
Under federal law, minors should normally be transferred to a Health and Human Services (HHS) shelter within 72 hours of their detention.
An HHS spokesman told the Associated Press news agency that a “minority of cases exceeding 72 hours have generally involved exceptional circumstances”.
What’s been the reaction?
US Customs and Border Protection (CBP) acting commissioner John Sanders said the agency was “saddened by the tragic loss of this young man” and said they were “committed to the health, safety and humane treatment” of those in custody.
The Congressional Hispanic Caucus, a group of 38 Democratic members, have demanded a federal investigation into the child deaths and detention on the border.
“Nobody had died for 10 years [in detention]. And in the last six months, you’ve had five deaths,” he told reporters.
“They’re concealing the truth of these atrocities to the American people,” Mr Castro told a press conference on Tuesday.
But President Trump blamed the Democratic Party for the death, saying they were making things “very, very dangerous for people” by not supporting changes to the system.
“We could have it all worked out,” he told reporters.
Mr Trump unveiled long-awaited immigration plans in May favouring English-speaking better-educated workers.
Democrats dismissed them as “dead-on-arrival” for failing to address the issue of “Dreamers” – people brought to the US as children who have no legal right to remain.
What’s the situation at the border?
According to official statistics, more than 300,000 people were apprehended at the southern border between January and April, with numbers rising every month.
Officials say they do not have the facilities to handle the rising numbers of migrants.
But opposition lawmakers, rights groups and international charities have condemned the treatment of people at the border, pointing to cramped holding pens and shoddy accommodation.