A car hit a mother and her two young sons as they crossed the street Tuesday night in Southwest Miami-Dade, killing one of the boys, police said.

The accident happened about 6:40 p.m. near the intersection of Southwest 268th Street and 137th Avenue, Miami-Dade police said. Donelle Griffin, 42, was crossing 268th Street with her sons Jaheim Haddo, 8, and Ameer Blair, 7. They were almost to the other side when they were hit by a green, 1990s-model Crown Victoria.

Blair died soon afterward. Griffin was taken by paramedics to Homestead Hospital, and her surviving son was taken to Miami Children’s Hospital.

Witnesses said it looked like the family had just come from the Diaz Supermarket at 13501 SW 268th St. After the crash, groceries were strewn across the street. The three were not crossing the street in a crosswalk, police said.

Two people who were at a nearby gas station convenience store when the crash happened said they believed two cars hit the family. However, police spokesman Detective Roy Rutland said that, based on the evidence and the witnesses investigators had spoken with, it appeared that only one car was involved.

Curtis Nelson, 44, said he was sitting on a crate near the store when he heard a boom. He ran into the street, found one of the boys and got him out of the road. He went back and found the mother and the other son.

“He was twisted like spaghetti,” Nelson said.

Nelson said he tried to keep other vehicles from hitting them. Afterward, he said it made him think of his own family, which has crossed the same street many times.

“It could have been me and my grandbabies,” he said.

The driver, Dagoberto Trevino, 25, was in police custody Tuesday night and has not been charged with a crime.

The two passengers in the green car at the time of the crash were not injured.

Miami Herald staff writer Alexandra Leon contributed to this report.