Eight immigrants were killed on Monday afternoon when a pickup truck they were riding in crashed head-on into another pickup in a police chase in southwestern Texas, the authorities said on Tuesday amid a deepening humanitarian crisis along the Mexican border.

The incident occurred on U.S. Highway 277 roughly 30 miles north of the border city Del Rio, according to the Texas Department of Public Safety, which said that the Dodge pickup with all the immigrants had evaded Texas State Troopers before the crash.

The police didn’t elaborate on what had led to the chase, but said the Dodge had caused a head-on collision with a Ford F-150.

The eight passengers at the Dodge who were killed, all undocumented immigrants, died at the scene, according to the Department of Public Safety.

The driver of the Ford and a kid who had been a passenger of the truck were hospitalized in stable condition, along with a ninth passenger of the Dodge pickup truck, according to a preliminary accident report.

The driver of the Dodge ran off after the crash but was captured a short time later, according to the authorities, who identified him as Sebastian Tovar, 24. They stated that Mr. Tovar was in custody and was hoping to be charged by the state.

The loss of life punctuated a period of intensifying scrutiny of the Biden administration over states along the Mexican border, where there’s been a sharp uptick in the amount of migrants from Central America seeking entry into the United States. On Tuesday, the head of the U.S. Department of Homeland Security warned that immigration authorities expected to create more apprehensions over the border this year than anytime in the last two decades.

The accident came less than two weeks after 13 people were killed in one of the deadliest border-related crashes in recent decades when a big rig slammed into an S.U.V. crammed with more than two dozen people in California.

Alejandro N. Mayorkas, the homeland security secretary, characterized the situation as “difficult” in a statement on Tuesday.

We’re on pace to experience more people on the southwest edge than we have in the last 20 years, Mr. Mayorkas said. “ We are expelling most single adults and families. We are not expelling unaccompanied children. ”

The people who died in Monday’s accident were all Mexican nationals between the ages of 18 and 20, The Associated Press reported, citing data from the Val Verde County sheriff, Joe Frank Martinez. Seven of them were men and one was a girl, the sheriff said.

Photos of the crash scene published by the Department of Public Safety showed what appeared to be the Dodge pickup upside-down in the grass on the side of the street. Pieces of wreckage could be seen strewn on the road and the shoulder.