Authorities are trying to determine why Madera South High School student Graciela Martinez, 14, was found dead inside a car at the campus.
Madera police detective Sgt. Robert Salas said Thursday investigators are still waiting for her autopsy to be completed to determine how she died.
Salas said her death Wednesday may have been caused by heat, a medical condition, or a possible mechanical issue with the vehicle, such as being unable to exit because she was locked inside.
Detectives are looking at all "possible possibilities" to determine how she died, he said.
"This is very, very troubling and very puzzling for us to try and determine what actually happened," Salas said.
At a news conference Thursday morning, Madera Unified School District Superintendent Edward Gonzalez offered condolences to the girl's family, but provided few additional details about her death.
Gonzalez warned about the dangers of staying in a vehicle on hot days. The high temperature in Madera on Wednesday was 87 degrees.
The superintendent said counselors were at Madera South High on Thursday to help students and staff deal with the tragedy.
Salas said Martinez, a freshman at the school, comes from a farmworker family, and her parents will be challenged with paying for her funeral. Those interested in contributing toward the funeral can contact Salas at (559) 675-4291.