A 3-year-old child died while traveling on a bus chartered by the state of Texas as it transported asylum seekers from the border city of Brownsville to Chicago as part of Gov. Greg Abbott’s program to send migrants from Texas to Democratic-run cities in other states, officials said.

The child’s parents were also on the bus when the child began showing symptoms of an illness, including a fever and diarrhea, before losing consciousness, according to Representative Joaquin Castro, a Democratic congressman from San Antonio whose office was briefed on the death.

The Texas Department of Emergency Management, which runs Mr. Abbott’s busing program, confirmed the child’s death in a statement and said that every passenger on the bus had been processed by U.S. Customs and Border Protection and that, before the migrants boarded the bus, their temperatures had been checked and they had been asked if they needed medical assistance.

“Following this check, prior to boarding, no passenger presented with a fever or medical concerns,” the statement said, without specifying when the death had taken place. A spokesman did not respond to requests for additional information, including the timing of the death, the nature of the illness, the name or sex of the child or the country of origin of the family.

The Illinois Department of Public Health told The Associated Press that the death had taken place on Thursday.

The death appeared to be the first attributed to Mr. Abbott’s program of busing migrants from Texas to cities like New York, Washington and Philadelphia. Roughly 30,000 migrants have been bused out of Texas since the program began in April 2022, including more than 4,600 to Chicago. Texas officials have said that only migrants who agree to the travel are placed on buses.

A spokesman for Mr. Abbott did not respond to a request for comment.

The child began showing symptoms in Illinois and was taken to a hospital in the town of Salem, about 250 miles south of Chicago and 1,200 miles north of Brownsville, Mr. Castro said. The child’s parents had hoped to get to Indiana, where they had relatives, he said.

The child died in the hospital, according to the Texas emergency department.

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

The Illinois State Police were investigating the death, according to a spokeswoman.

Mr. Castro, in a joint statement with Representative Jesús García of Illinois, called on the federal government to intervene to stop the busing program.

“For months, Operation Lone Star has trafficked asylum-seekers across the country in squalid conditions,” the statement said. “The Biden administration has an obligation to stop them.”