The girl, a class 12 student, was alone in her house at the time of the incident yesterday, they said.
The police said that prima facie it appears to be a case of suicide.
The girl's family, however, alleged that she was killed, the police said.
The family claimed that three days ago a man had allegedly threatened to kill the girl if she did not marry him, the police said.
"Allegations of her parents are being investigated. The accused has been detained for questioning. Further investigations will be as per the evidence found during investigation and post mortem report," Bisrakh police station incharge Ajay Sharma said.