CHICAGO (CBS)– The 15-year-old girl who was the victim of a frightening attack caught on video might also have been the victim of a sexual assault, police said, but investigators are still trying to piece together what happened to the girl while she was missing for five days.

Detectives began investigating the attack on Tuesday, after CBS 2 sent the video to police.

In the video, the victim is seen trying to defend herself as another girl continues to corner her and hit her – with the help of others. Police said they do not know exactly where or when the attack happened, but those who know the young victim say it happened Saturday near 81st Street and Exchange Avenue in the South Chicago neighborhood.

Chicago Police Department Jose Jara said police are also investigating whether the girl was sexually assaulted.

“It seems that’s the route it’s going,” he said.

Jara said it’s unclear whether that happened before or after the attack that was caught on video.

Police said the girl was beaten by “so-called friends” who police are now looking for as the attackers.

“It is believed that the victim was invited out by some girls who are so-called friends who were eventually the offenders in these disgusting incidents,” Jara said. “It’s very concerning and disgusting that the victim’s so-called friends may eventually be the offenders in these incidents.”

Community activist Stringer Harris, who has been acting as a spokesman for the victim’s family, said the attack stemmed from a disagreement between friends.

Harris said the earlier on the day of the attack, the victim’s friends were planning to “meet up with a guy to have some type of relations with.”

He said the 15-year-old was against the plan and her friends got upset. The 15-year-old tried to approach police to “let them know what was going on,” but the friends stopped her, according to Harris.

The girl then walked through an alley to leave, with the plan of getting on bus. Harris said a friend approached her and asked what she was going to say to police.

Harris said the girl said “nothing,” and “leave me alone.”

“One of her friends hit her in the face, striking her in the head, that left lacerations on her forehead,” Harris said. “Another friend attacked her brutally and beat her and another gentleman was there as well.”

He said the incident involves five females and one male ages ranging from 15 to 18.

“It’s a shame,” the spokesperson said. “This shouldn’t happen to anyone.”

Jara said the teen had been missing for five days before she was reported missing on Tuesday, but he couldn’t explain why she hadn’t been reported missing sooner.

The girl disappeared after the attack, and was located days later by a friend on the on the CTA Blue Line at Harrison and Kedzie.

The friend contacted the teen’s family, who took the 15-year-old to the police station. She later was treated and released at Comer Children’s Hospital.

Jara described incident as “sick and disgusting crimes.”

He indicated sexual assault is being investigated in this case, “based on initial testimony from the victim herself.”

Jara said there may be initial charges based on interviews with the witness.

Chicago police are seeking the public’s help in locating witnesses and suspects.