AUSTIN, Texas (AP) — A three-year-old child riding one of Texas’ migrant buses died while on the way to Chicago, officials said Friday, the first time the state has announced a death since it began shuttling thousands of migrants from the US-Mexico border last year.

Texas authorities confirmed a child’s death in a statement Friday but did not say where the child was from or why they became ill. The Illinois Department of Public Health said the child was three-years-old and died Thursday in Marion County, in the southern part of that state.

“Every loss of life is a tragedy,” the Texas Division of Emergency Management said in a statement. “Once the child presented with health concerns, the bus pulled over and security personnel on board called 9-1-1 for emergency attention.”

Texas has bused more than 30,000 migrants to Democratic-controlled cities across the US since last year as part of Republican Governor Greg Abbott’s sprawling mission on the border, called Operation Lone Star. The operation has come under a burst of new scrutiny in recent months over additional hardline measures the governor has authorised in the name of deterring migrants from crossing from Mexico.

The Biden administration is suing Texas over wrecking ball-sized buoys placed on the Rio Grande this summer, saying the water barrier poses environmental and humanitarian concerns. Texas has also begun separating some migrant families on the border in what marks a shift by state police, who have previously said that families should stay together.

Abbott spokesperson Renae Eze referred questions Friday night about the child’s death to the state’s emergency management agency, which has operated the bus program since it launched in 2022.

The child received treatment from paramedics and later died at a hospital, according to the agency. The bus departed from the Texas border city of Brownsville. All passengers had their temperature taken and were asked if they had any medical conditions, according to Texas’ emergency management agency, which did not immediately respond to requests for more details Friday night.

Illinois officials said in a statement they were working with health officials, state police and federal authorities “to the fullest extent possible to get answers in this tragic situation.”