Staffers at a school for the emotionally disturbed conducted their own investigation of a 13-year-old girl's rape and even tried to collect evidence before reporting the attack, a police chief said Tuesday.

"I'm not certain it's criminal but it's certainly not advisable," said Mount Pleasant police Chief Louis Alagno. "They should be calling, notifying the police and calling in the professionals."

He said the school delayed calling police for nearly four hours after the Monday night attack at the Hawthorne-Cedar Knolls School in Hawthorne, about 25 miles north of New York City. Three teenage boys were arrested and charged as adults.

The Jewish Board of Family and Children's Services, which operates the school, issued a statement saying it was investigating the incident and cooperating with police, but did not address the allegation of the delayed call. It said it would not discuss individual children.

Alagno, whose jurisdiction includes Hawthorne, said the attack occurred at about 7:30 p.m., when the girl was forced into a vacant school building. She reported the attack to school staff right away, but police were not called until 11:30 p.m., he said.

"Staff members actually commenced their own investigation, including attempting to collect forensic evidence," Alagno said.

He did not say whether the delay or the staff investigation harmed the police investigation, but said he would be taking the issue up with school officials.

Arrested were three residents of the school: Mario Rivera, 15, of Brooklyn; Stanford Beaulieu, 15, of the Bronx; and Gyale Taylor, 16, of Yonkers. They were charged as adults with first-degree rape, Alagno said. They had not yet been arraigned and did not have lawyers of record.

The Jewish Board's Internet site says the school houses 104 boys and girls aged 8 to 18 who receive treatment, education and supervision for emotional problems. Youths are referred by New York City and state agencies.

In 2002, violence erupted at another school for troubled teens in Mount Pleasant, the Pleasantville Cottage School, when eight girls aged 15 and 16 beat and burned a counselor. The counselor spent several days in a hospital and the girls were sentenced to prison terms ranging from one to 10 years.