The death toll has risen to eight after an SUV slammed into a crowd of people waiting for a bus Sunday outside a migrant shelter in the border city of Brownsville, Texas. At least 10 others were injured, police said, as they prepared to arrest the hospitalized driver.

With no bench at the unmarked city bus stop, some of the victims were sitting on the curb around 8:30 a.m. local time, when the driver hit them, surveillance video from the Bishop Enrique San Pedro Ozanam Center showed.

Brownsville police investigator Martin Sandoval, who confirmed the latest death Sunday evening, said police did not know whether the collision was intentional.

Shelter director Victor Maldonado said the SUV ran up the curb, flipped and continued moving for about 60 metres. Some people walking on the sidewalk about nine metres from the main group were also hit, Maldonado said.

Witnesses detained the driver as he tried to run away and held him until police arrived, he said.

The driver was taken to hospital for injuries sustained when the car rolled over, Sandoval said. There were no passengers in the car and police didn't immediately know the driver's name or age.

"He's being very unco-operative at the hospital, but he will be transported to our city jail as soon as he gets released," Sandoval said. "Then we'll fingerprint him and [take a] mug shot, and then we can find his true identity."

Police also retrieved a blood sample and sent it to a lab with the Texas Department of Public Safety to test for intoxicants.

Brownsville has long been an epicentre for migration across the U.S.-Mexico border, and it has become a key location of interest for next week's end to pandemic-era border restrictions known as Title 42. The Ozanam shelter is the only overnight shelter in the city and manages the release of thousands of migrants from federal custody.

Maldonado said the centre had not received any threats before the crash, but did afterward.

"I've had a couple of people come by the gate and tell the security guard that the reason this happened was because of us," Maldonado said.

The shelter can hold 250, but many who arrive leave the same day. In the last several weeks, an uptick in border crossings prompted the city to declare an emergency as local, state and federal resources coordinated the enforcement and humanitarian response.

"In the last two months, we've been getting 250 to 380 a day," Maldonado said.

While the shelter offers migrants transportation during the week, they are also free to use the city's public transportation.
"Some of them were on the way to the bus station, because they were on their way to their destination," the director said.

U.S. Rep. Vicente González said Sunday that local officials are in communication with the federal government about the crash.

"We are all extremely sad and heartbroken to have such a tragedy in our neighbourhood," he said.