A family friend of the girl beaten by a group of teens in Brooklyn called the attack “savage” Friday — as a witness described how she lay bleeding on a sidewalk.

“This was savage. I don’t understand,” Tony Herbert, a friend of the victim’s mom, told The Post. “I’m destroyed.”

Herbert, 55, said he was baffled by what may have motivated the beating.

“Whatever it was, it wasn’t worth this kind of stupidity,” he said. “It’s sad that this would take place.”

A mob of teenagers unleashed the stunning beatdown on the 15-year-old in Crown Heights Thursday afternoon, and then took a pair of Air Jordan sneakers off her feet, according to cops and surveillance camera footage.

Herbert said the girl — who was rushed to a NYC Health & Hospitals branch and later released — is recovering and “may have to go see another doctor.”

Meanwhile, a witness at a hair salon near the site of the attack, on Utica Avenue near Sterling Place, described the gut-wrenching moments after the mob of teens fled with the girl’s shoes.

“I saw this little girl on the ground and they were putting bandages around her head and it was so sad,” said Jennifer, a 35-year-old hairstylist, who works at Diamond Kouture. “Her sneakers were off and she was bleeding from her head.”

She added, “When they find [those] kids, they need to lock them up and throw away the key. That little girl was unconscious on the ground.”

Surveillance camera footage from the attack shows one of the ruffians getting a running start, then leaping onto the girl and kicking her in the head.

The rest of the mostly male gang then rushes from across the street to join in the attack. They mercilessly punch and kick her in the face and chest while surrounding her, the footage shows.

Police had made no arrests and named no suspects Friday afternoon.