By Monica Antonio (media@latinospost.com) | First Posted: Sep 13, 2015 06:00 AM EDT

The lifeless body of a 19-year-old student with special needs was found inside an empty school bus in the parking lot of Whittier Union High School District in California on Friday afternoon, per Whittier Daily News.

Officials from the Los Angeles County Fire Department and Whittier Police initially reported the incident as a patient in "full arrest" after the police responded to a "man down" report on a bus.

According to a report from The Washington Post, the mother called the school to alert that her child was missing as he did not arrive home on Friday afternoon. The victim normally leaves school at 2:30 p.m. and comes home at 4 p.m. The police immediately conducted a search and located the victim in the bus parking lot, which, as per Whittier Daily News, is located along Mulberry Drive between Painter and Greenleaf avenues.

"The bus company, Pupil Transpiration (Cooperative), driver received a call from dispatch that a student was missing. He (returned) to his bus and that’s where he found this young man unresponsive," said Whittier police officer Brad White.

The Washington Post further reports that those who responded to the scene (bus drivers and police officers), tried to revive the victim, who was found "slumped in the aisle," through CPR. At 4:33 pm, the victim was pronounced dead. The news outlet further added that on Friday, the temperature in the area peaked at 95 degrees.

White, via Whittier Daily News, further noted that the cause of the student's death was "unknown." Police labeled the death as "suspicious" because there were "no obvious signs of trauma on the body." The report also states that the reason the teen, who attended Sierra Education Center’s transitional program, did not alight with other students was not determined and unclear. The bus driver is now in full cooperation with authorities to help solve the incident.

Whittier Union High School District superintendent Sandra Thorstenson released an official statement regarding the tragic incident, saying, “This tragedy has devastated all of us. We are still gathering information about what happened. The district is calling for a speedy and thorough investigation to determine how something like this could happen."

“Our hearts are with our student’s parents and family — we’re all grieving. We’re making ourselves, our counseling services and our staff available to his family and to our students and staff who were close to him," she added.

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