BROWNSVILLE, Texas >> The driver of an SUV that killed eight people when it slammed into a bus stop in Brownsville, Texas, has been charged with manslaughter, police said today as investigators tried to determine if the crash was intentional.

Authorities believe driver George Alvarez, 34, of Brownsville, lost control after running a red light Sunday morning, and plowed into a crowd of Venezuelans outside a migrant center.

Police Chief Felix Sauceda said Alvarez was charged with eight counts of manslaughter and 10 counts of aggravated assault with a deadly weapon. Officials are awaiting toxicology reports to determine whether Alvarez was intoxicated, Sauceda said, adding that there was no motive that he could discuss.

The SUV ran a red light, lost control, flipped on its side and struck 18 people, Sauceda said at a news conference this morning. Six people died on the scene and 12 people were critically injured, he said. Officials have said the death toll later rose to eight.

Alvarez tried to flee, but was held down by several people on the scene, he said. His bail was set at $3.6 million.

Victims struck by the vehicle were waiting for the bus to return to downtown Brownsville after spending the night at the overnight shelter, said Sister Norma Pimentel, executive director of Catholic Charities of the Rio Grande Valley.

Most of the victims were Venezuelan men, shelter director Victor Maldonado said. Brownsville has seen a surge of Venezuelan migrants over the last two weeks for unclear reasons, authorities said. On Thursday, 4,000 of about 6,000 migrants in Border Patrol custody in Texas’ Rio Grande Valley were Venezuelan.

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