A 7-year-old boy who’d stopped in a Bronx fast-food joint for an ice cream with his father and sister was killed Thursday after a driver backed his SUV through the front window and pinned the boy against a wall, his family said.

“When he was in the ambulance, his mother said, ‘Everything will be OK,’ and he said, ‘OK, mommy. I’ll be here waiting for you,’” little Ethan Villavicencio’s aunt, Taisha Alameda, said through tears at Jacobi Medical Center, where the boy died.

Ethan, his 5-year-old sister Maya, and their 34-year-old father had ducked into the Kennedy’s Chicken and Sandwiches on Westchester Ave. near Colonial Ave. in Pelham Bay while waiting for their mother, 26-year-old Natasha Villavicencio, to get out of a nearby appointment around 5:30 p.m., relatives said.

They were sitting at a booth near the window when the treat turned into unimaginable horror. A Mercedes-Benz SUV reversed into the restaurant, shattering glass, overturning tables and pinning the boy against a side wall, witnesses said.

“There was a crater where the boy hit the wall,” said bus driver Luis Cruz, 52.

Ethan lay on the floor, conscious but barely able to move, Cruz said. His sister and father stood over him.

“The father was a bloody mess. He was covered with blood and he was trying to tend to his son. The blood from his face was dripping down on the boy,” Cruz said. “It was heartbreaking.”

Police sources said the driver, Kwasi Oduro, was apparently trying to back into a parking spot when he lost control, then took off as a bystander tried to stop him, witnesses said.

“The SUV was trying to get away and a guy grabbed the door handle and actually opened the car door. He tried to pull the driver out but he stepped on the gas and pulled away,” Cruz said.

Other bystanders ran after the car and flagged down traffic agents, who nabbed the 73-year-old Oduro two blocks away.

Ethan’s horrified mom ran to the restaurant and held the boy’s hand in the ambulance on the way to the hospital.

Maya, who had arm injuries, and the father, who had cuts to his head, were both treated at Jacobi Medical Center, where family members gathered late Thursday.

Ethan “wanted ice cream so they went in to get ice cream. First time ever that they were there. Just for ice cream and this happens,” Alameda said.

“Tomorrow he had a speech in class he practiced so hard for, and Saturday he was supposed to go to the beach,” she sobbed.

“Everywhere he went, he danced. He gave life to everyone.”

As for the driver, Alameda said, “Why? Why did he do that?”

Police charged Oduro with leaving the scene of an accident that resulted in a death and injuries. He was awaiting arraignment Friday morning.