The police said a Facebook video found by a mother of her 16-year-old being sexually assaulted while unconscious at a house party in Providence, R.I., had led to charges against eight men.

The teenager woke up after a night of partying at a Providence, R.I., house to find herself naked in a shower, surrounded by men who were laughing and taking pictures, the police said.

She went to the police almost immediately, but the case stalled with little to go on beyond the girl’s painful memories from that night in December. Then, in March, the girl’s mother found a video of her daughter being sexually assaulted that one of the perpetrators had posted on Facebook.

The mother took out her phone, recorded the video on her computer screen and sent the recording to the police.

“That’s when the investigation really heated up,” Maj. David Lapatin of the Providence Police Department said in an interview on Wednesday. “We were able to see who was there. We were able to see faces. We were able to see the actual act, of first-degree sexual assault.”

On Wednesday, the police said the mother’s discovery of the Facebook video helped them charge eight men with sexually assaulting the 16-year-old girl after she lost consciousness at the house party on Dec. 20, 2019.

Col. Hugh T. Clements Jr., chief of the Providence police, said the assault was one of the worst he could recall in his 35 years with the department.

“The incident is horrifying, devastating, disturbing on so many levels to this young girl, to her family and to this community,” Chief Clements said at a news conference.

He said the teenager had been offered counseling, housing and other services, and he thanked her and her family for coming forward to report the crime. Not only had she helped identify the men who assaulted her, he said, but she also faced the possibility of testifying in court and being sharply questioned by defense lawyers.

“I commend her bravery, her courage and her family for sticking by her,” the chief said.

“I give her a lot of credit,” he added.

The police said six men — Keith Erving Colon, 24; Jose Vargas, 18; Carlos Chacon, 19; Malcolm Baptista, 18; Luis A. Cabrera, 18; and Luis Luna, 19 — were arrested last week and charged with assault with intent to commit sexual assault and conspiracy.

A seventh man, Richard Tarell Chester, 19, was arrested and charged with first-degree sexual assault, the police said. The eighth, Carlos D. Vasquez, was being sought on Wednesday on charges of assault with intent to commit sexual assault and conspiracy.

Suspects arrested and one still at large on charges of sexual assault of a teenager at a house party in Rhode Island.

Lawyers for several of the men did not immediately respond to messages on Wednesday. Chad F. Bank, a lawyer for Mr. Luna, and Nicholas Obolensky, a lawyer for Mr. Cabrera, declined to comment.

On the run