A northern California mother, father and step-father of a 15-year-old girl reportedly are behind bars after police accused them of assaulting and kidnapping a teenage boy they found in their daughter's bedroom in an apparent hate crime.

The 15-year-old's biological father, 49-year-old Luisandor Suarez, her mother, 46-year-old Haydee Arguello, and her step-father, 46-year-old Wilfredo Amaya, allegedly abused a 17-year-old African American boy physically for 30 minutes and threatened to kill him on Thursday, according to San Bruno Police and local reports. San Bruno is about 15 minutes from San Francisco.

The boy went to the police department and reported that he had been held against his will, assaulted and threatened by the three suspects at a home in San Bruno, police said.

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"These family members ultimately restrained the victim using a rope. Held him against his will, assaulted him multiple times and even threatened to kill him," according to a news release sent to Fox News from the San Bruno Police Department. The news release said the teen eventually was "released" and ran away from the home.

Police said doctors later treated him at a nearby hospital for non-life-threatening injuries.

The 15-year-old's sister claimed her parents thought the boy was an intruder and acted in self-defense, KGO-TV reported.

"They were so scared because they found someone in the closet. They jumped because everyone was sleeping and this guy started kicking my step-father and trying to kill him," Belkys Gomez said.

Katherine Gomez, who was in the home during the alleged attack, reportedly said, "He (the teen) punched her and then my step-dad, of course, is not going to let anyone hit his wife. They tried to stop him and he was acting very violent so they grabbed a rope to try to tie him down and ask him why he was at the house."

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Police said the three suspects used racial slurs during the alleged attack.

"The victim reported that throughout this attack the suspects yelled at him using multiple racial slurs, and he believed his race to be a motivating factor in the attack," police said in the news release, adding that "the victim is African-American, and the suspects are of Hispanic descent."

Katherine Gomez reportedly said the racial accusations were "not true at all."

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Suarez, Arguello and Amaya were arrested and faced charges including kidnapping, assault with a deadly weapon and criminal threats.

The 15-year-old was in the custody of Child Protective Services, KGO-TV added.