UPDATE: 3 Teens Arrested For Beating Mentally Challenged Delaware Man

NEWARK, Del. (CBS) — New Castle County Police say they've arrested a 13 and 14-year-old boy in connection to the abuse of a Newark mentally disabled man.  Monday night, authorities announced a third teen has turned himself in to police and is facing charges.

A viral video on Instagram shows a group of teens beating the 26-year-old, slamming him to the ground and kicking him as he pleads for them to stop.

A teen who was in the video tells CBS3 Eyewitness News news he helped file a report. He didn't want to reveal his identity for fear of retaliation.

"The right thing to do was call the cops," he said. "If you beat up a mentally disabled person, you should be locked away for good.

He says the attacks took place in the woods near the YMCA of Newark and at the Harbor Club Apartment complex, also in Newark.

The victims' family tells CBS3 the video left them speechless.

"I think they were bullies to be beating on people like that," said his little sister, Winter Brooks. She says he suffers from a developmental disorder called Williams syndrome.

His Godmother says he trusted the group of teens who hurt him to be his friends, and that he's suffering emotional along with his physical trauma.

"He's not doing too good he's ashamed about it happening, he's embarrassed," said Debra Jackson.

Police say they are still conducting interviews and more arrests are possible.

UPDATE: On Monday, New Castle County Police announced a 14-year-old boy had turned himself in at police headquarters.

Police say the three teens face the following charges: offensive touching, assault of a vulnerable adult and conspiracy in the third degree.

Officers are continuing their investigation.  Police ask anyone with information to call the New Castle County Police Department at (302) 573-2800 or Crime Stoppers at (800) TIP-3333.