WOODLAND PARK, Colo. -

Woodland Park Police are investigating how a 16-year-old girl died at her home before the start of the school day on Monday.

The student has been identified as Anna Dille of Woodland Park. Police say her parents discovered she was dead when they tried to wake her up in the morning.

An autopsy was conducted on Tuesday but the cause of death is still not known. The Teller County Coroner says there was no physical trauma and they are focusing on natural causes. Laboratory analyses may take as long as four to six weeks.

Police said they received a medical emergency notification of a person not breathing just before 8 a.m. Monday. Officers, paramedics and fire rescue personnel responded to the home and found Dille deceased.

Teller County Coroner Al Born said the girl was not under a doctor's care.

Friends say Dille was a sophomore at Woodland Park High School. The school released a statement on Monday afternoon asking the community to respect the family's privacy as they begin coping with the tragic loss of their daughter.

Aaron Archuleta, a friend and classmate of Dille, said she mentioned she wasn't feeling well and went home when he saw her for the last time a week ago.

"We were joking in the hallway," said Archuleta. "We were smiling (and) having a good time, and I gave her a hug. She was really nice to me. She was always willing to help her friends."

Another classmate, Carrie Makris, spoke of how the school coped with the sudden death.

"There was a morning service at the library," Makris said. "A lot of people went to it."