The mother of one of the teens who turned themselves in for the savage sidewalk beating of a 15-year-old girl “wanted to kill him with my bare hands” when she saw the caught-on-camera attack, she told The Post Saturday.

“I’m angry and very disappointed in him. I did not teach him to act like an animal in the street,” said Donna Howell, 42, whose 14-year-old son, Alex, was charged Saturday with robbery and gang assault in connection with the shocking beatdown.

The victim had been walking along Utica Avenue in Crown Heights Thursday when she was ambushed by more than a dozen teens, authorities said.

Video footage captured the group punching and kicking the girl in the head as she lay helpless on the pavement, finishing off the attack by snatching the black and white Air Jordan 1 Retro sneakers off her feet.

“I watched the video twice, it kept popping up on my feed,” said Howell, who was getting her eyelashes done at the time. “I realized, that’s my kid. I just went numb. [The eyelash technician] said, ‘You look like you just saw a ghost.’ I was beyond shocked.”

“When I saw the video, I wanted to kill him with my bare hands,” she said of her son.

“Why would you stomp on somebody you don’t know? You don’t jump on a woman,” she said.

“If I was that girl’s father, I would want to kill all of them. This is unacceptable on all levels. You don’t ever put your feet on someone, and you definitely do not treat a female like that.”

Howell says she confronted her son, who is in eighth grade, and forced him to turn himself in at the 77th Precinct stationhouse.

“He has been in trouble before, but not this kind of trouble. I don’t expect him to be perfect, but I expect him to be respectful in the street,” she said.

Four other teenage boys also turned themselves in and were charged, police said.

Alex, whose surname is being withheld due to his age, was arraigned at Kings County Criminal Court on Saturday night along with three of the other boys — ages 14, 16 and 17 — on charges of second-degree robbery and gang assault.

Jordan Rossman, the assistant district attorney, described the boys as “strangers” to the victim.

The four teens arraigned Saturday night were released under orders from Judge Deepa Ambekar to follow individual curfews ranging from 3 p.m. to 4:30 p.m.

The fifth teen was held pending an arraignment Sunday.

Investigators believe the group attack may have been retaliation for a fight earlier in the school day when the girl allegedly beat up another student, sources said.

But her friends insisted to The Post the victim is a “quiet” basketball player.

“She goes to school, and she is a basketball player — that’s all she does. She doesn’t have problems with anyone,” said 13-year-old pal Jacob Black.

The traumatized teen has a concussion and bruises and is scared to leave her home, relatives said.

“My granddaughter, her spirit is broken,” said her grandmother, Pamela, adding that her own spirit is broken, too.

Police continue to search for additional suspects.

“I literally felt like I have to throw up since yesterday. I can’t eat,” Howell told The Post, adding that her son would be “on punishment” for years to come for his role in the incident.

“My heart breaks for the victim’s family. I’m just very, very sorry. I feel very, very bad for her.”