Materials recovered from the home of a Catoctin High School student after a reported threat against the school. (Frederick County Sheriff's Office)

Authorities said they stopped a Frederick County teenager after her parents reported that she was planning violence at her high school.

The Frederick County Sheriff’s Office said the 18-year-old student at Catoctin High School in Thurmont was transferred to a hospital for an emergency evaluation because she was deemed a threat to the school and herself. She remained hospitalized Monday.

The Sheriff’s Office identified the student as Nicole Cevario. Investigators said in a statement that they obtained an arrest warrant charging her with possession of explosive material with intent to create a destructive device and possession of incendiary material with the intent to create a destructive device.

Officials said that they believe that the threat was serious and that Cevario was “actively acquiring materials needed to execute” violence at Catoctin High School, the statement said. Authorities said they found a shotgun, ammunition and bomb-making materials that included pipes, shrapnel, fuse material and fireworks at the teenager’s home.

Materials recovered from the home of a Maryland student after an alleged threat against a high school. (Frederick County Sheriff's Office)

Officials said they also found detailed plans in a journal for carrying out a shooting on April 5.

Based on the journal, authorities said, the teenager had been “planning this event for some time and compiling intelligence on behavior activities.” She had notes on the school’s emergency procedures involving security and drills, along with “intelligence” on security personnel who are assigned to the school, according to the Sheriff’s Office.

Her journal also included a timeline of “how she was going to execute the plot,” as well as her “expectations at each stage of the event,” authorities said.

Maj. Tim Clarke, a sheriff’s spokesman, said that Cevario’s parents reported concerns about their daughter to school officials Thursday and that law enforcement became involved. The student was removed from a classroom at the school that day and taken to a hospital.

Clarke said officials believe Cevario was “acquiring items to go through with the threat.” No weapons or explosive devices were taken to the school, officials said. He said that officials are “confident that the safety” at the school is “fine based on an investigation.”

This potentially could have been a serious incident,” Clarke said. In a statement, officials said Cevario had plans and equipment that would have “caused a significant life safety event” if she had “followed through with the threat.”

Materials recovered from the home of a Catoctin High School student in connection with an alleged threat against the school. (Frederick County Sheriff's Office)

Officials said they believe that Cevario made the plans alone and that no one else was involved.

In their statement, authorities praised Cevario’s parents for letting people know of the potential threat and said they were being cooperative in the investigation.

“They absolutely did the right thing,” the statement said.

Anyone with information is asked to contact Frederick County authorities at 301-600-2583.