Police on Wednesday were investigating allegations that members of a high school wrestling team put a noose on a brown practice dummy, chained a black teammate to a locker and made racial remarks.
The boy and his mother told police last week about the alleged May 4 incident, the Los Angeles Times reported.
"The district welcomes the investigation and is fully cooperating" with police, said a statement Wednesday from Tim Cuneo, superintendent of the Santa Monica-Malibu Unified School District.
The teenager walked into the wrestling room at Santa Monica High School and allegedly found a brown practice dummy with a noose around its neck. He then went to the locker room to change but was grabbed by two white students who bound his pants to a locker with a cable and lock and made racial remarks, according to an account given to authorities that was cited by the Times Wednesday.
Santa Monica Police Sgt. Richard Lewis told the Times that students could potentially face assault and battery charges.
The boy's mother, Victoria Gray, told the newspaper that the school never notified her of the alleged attack and she only learned about it from another parent on May 31.
A June 16 email to parents from Principal Hugo A. Pedroza called the alleged incident a "serious matter that warranted a swift and appropriate response."
He said the students were suspended or received other discipline, while the entire wrestling team received sensitivity training, the Times said.
A call to the principal's office and an email left for the school's wrestling coach, Mark Black, were not immediately returned Wednesday.
A civil rights activist, meanwhile, urged the Los Angeles County district attorney's office to investigate.
The school's disciplinary action against the students was inadequate and its delay in reporting the attack was "a shameless cover-up of an apparent vicious racially motivated attack," said a statement from Earl Ofari Hutchinson, president of the Los Angeles Urban Policy Roundtable.
The students involved should be charged with hate crimes and anything less "sends the dangerous message that campus hate attacks will not be punished with speed and severity," Hutchinson said.