Seven people are dead after a speeding car wiped out a line of pedestrians in what witnesses and police said appeared to be a deliberate attack.

The horror incident in the city of Brownsville, Texas, happened on Monday (AEDT) near a shelter for migrants and homeless, it has been reported.

Witnessed have told of graphic scenes, with body parts strewn on the street, after the Land Rover slammed through the people waiting at a bus stop.

An unverified video circulating online shows a speeding four-wheel-drive slamming into a row of people sitting on the kerb.

There are also unverified videos of the awful blood-soaked aftermath.

Some migrants were among the dead, said Lieutenant Martin Sandoval of the Brownsville Police Department.

At least 10 more people were injured.

A man, described as Hispanic, has been arrested and charged with reckless driving and “more than likely” there would be more charges,” said Lieutenant Sandoval.

“We are doing an investigation in forms of intoxication to see if he was intoxicated at the time of the accident,” he said.

CNN reported that witnesses at the scene detained the driver until officers arrived.

Earlier, US media quoted police saying it appeared to be a deliberate attack targeting the pedestrians.

Brownsville, which is near the border with Mexico, has a population of 100,000, with nearly 95 per cent Hispanic or Latino.

“We grieve for the victims…who were run over outside a migrant shelter where people from around the world are seeking asylum and safety,” the American Civil Liberties Union said in a statement.

“We understand the motive is still under investigation. This horrific event comes after weeks of escalating anti-immigrant policy-making by Texas politicians and while the Biden administration considers imposing a new asylum ban aimed at deterring, rather than welcoming, migrants seeking protection.”

Victor Maldonado, director of the Ozanam migrant shelter, told CNN a staff member was confronted by a graphic scene after running outside to help.

“I’ve got a staff [member] who is in shock,” Mr Maldonado said.

-with AAP