A 3-year-old girl on one of Texas' migrant buses died on the route to Chicago, according to officials, the first death disclosed by the state since it began transporting hundreds of refugees and migrants across the US-Mexico border last year.

In a statement issued on Friday, Texas officials acknowledged the death but did not specify where she came from or why she became ill.

The Texas Division of Emergency Management called her death a tragedy, detailing that “once the child presented with health concerns, the bus pulled over and security personnel on board called 911 for emergency attention.”

According to the organization, the child was treated by paramedics and eventually died in a hospital in Marion County, Illinois.

The bus set off from the Texas border city of Brownsville on its way to Chicago as part of Republican Governor Greg Abbott's contentious migrant busing policy, which transports migrants and refugees from Texas to Democratic-run cities in neighboring states.

In recent months, the operation has been under increased attention due to extra tough tactics, such as floating obstacles authorized by the governor in the guise of discouraging asylum seekers from crossing from Mexico.

Answers still needed 

Illinois officials expressed they were cooperating with authorities and health officials "to the fullest extent possible to get answers in this tragic situation”.

US Representative Henry Cuellar, a Democrat, criticized Abbott for not working more closely with federal border security officials.

Cuellar stated that “You can’t use the migrants as political pawns. You still got to be accountable to taking care of them, especially if you’re transporting kids."

On Friday night, Abbott's spokesperson Renae Eze addressed queries concerning the child's death to the state's emergency management department, which has run the bus program since it began in 2022.

Abbot Tweeted Tuesday that the buses will continue "until Biden does his job and secures the border."

Read more: US fears end of Title 42 at US border means surge in migrants

New report details gruesome human rights violations at US border

Only last week, a  report issued by two Latin America-focused NGOs detailed that violations of human rights by US border police are "persistent" and that the lack or absence of accountability was problematic.

"Customs and Border Protection (CBP), the federal government's largest civilian law enforcement agency, has a persistent problem of human rights abuse without accountability," the report from the Washington Office on Latin America (WOLA) and the Kino Border Initiative (KBI) read.  

Violations of human rights by border agents range from deaths in custody amid unclear circumstances, abusive language, food deprivation, and the forceful separation of families. 

Last month, asylum seekers and advocates reported that an ICE detention center in Louisiana has insufficient medical care and unclean accommodations and is infamous for the mistreatment of detainees, an exclusive report by NBC News revealed.  

ICE has failed to address the issues in the year since immigration authorities vowed the facility would improve living conditions and reduce the number of people the facility holds.