All are students at Montclair High School. The attack allegedly took place Thursday afternoon at the home of the 18-year-old.
The mental capacity of the girl was still being determined, said Paul Loriquet, a spokesman for Dow's office. But Dow said after a news conference Tuesday that some of the charges faced by three teens relate directly to the victim's diminished capacity.
According to Montclair Police Chief David Sabagh, the victim told a girlfriend about the alleged attack on Friday, who then told authorities. The victim was treated at a local hospital on Friday and released, Dow said.
The examination at the hospital revealed evidence of sexual trauma, Dow said.
Authorities said the assaults happened after a number of teens came to the 18-year-old's unsupervised home between 11:30 a.m. and 4:30 p.m. on Thursday. According to Sabagh, classes at the high school were staggered to accommodate testing, so it was not clear if the teens were cutting classes.
Investigators were still interviewing potential witnesses, Sabagh said, and it was not immediately clear whether others witnessed the alleged assault or whether the incident was recorded on a cell phone camera or other device.
Three boys compelled the girl to perform sex acts on them, prosecutors said. The three then used force to assault her, Essex County Chief Assistant Prosecutor Robert Laurino said.
Authorities identified the 18-year-old as Romal Roberts. He and the 16-year-old boys were charged with aggravated sexual assault - that charge involves penetration - in an 18-count indictment.
The names of the 16-year-olds, who are juveniles, would not be released unless they are tried as adults.
Roberts was arrested Saturday and was being held Tuesday at the Essex County Jail on $500,000 bail. One 16-year-old was arrested at his home Saturday and the other surrendered Tuesday, prosecutors said. The younger teens were held at the county youth house.
Assistant Prosecutor Carolyn Murray said Roberts would likely be represented by a public defender at an arraignment on Wednesday. It was not immediately known if the juveniles had retained legal counsel.
A telephone message left at a number listed for the Montclair home was not returned Tuesday.
Evidence from the home was seized and is being tested, Loriquet said. Authorities have not yet determined if others were involved, he said.
Neighbors on the street where the alleged assault occurred described the worn-looking, two-story house as a place where numerous kids gathered and would often play ball in the street.
"There were always a lot of kids in that house, but I never had any trouble with them," said Janis Blackburn, who lives across the street. "They never bothered anybody, and they were always respectful of me."
Blackburn's son, Jose, said he knew Roberts from working as a substitute teacher in the Montclair school system. The younger Blackburn was stunned to hear the charges against a teenager he said didn't seem troubled or violence-prone.
"That's crazy - that doesn't seem like the Romal I know," he said. "He was a good person, he wasn't a fighter."
The alleged assault bears resemblance to a 1989 attack on a 17-year-old mentally retarded girl in neighboring Glen Ridge by schoolmates.
Several Glen Ridge High School athletes served prison terms after being convicted of the attack. The case was dramatized in an ABC television movie in 1999.
On Tuesday, Dow urged caution in drawing parallels to that case.
"All of us are familiar with the Glen Ridge case and investigation. I think it's too soon to make a strong comparison," Dow said. "Right now, we're investigating a case of a young teenage female victim and multiple male teenagers have been charged."
--- Associated Press writers Jeffrey Gold in Newark and Brad Haynes in Trenton contributed to this story.
