A 14-year-old girl told Saskatoon police "voices told her to do things" in the moments after a 15-year-old classmate was lit on fire Sept. 5 at Evan Hardy Collegiate.

The detail emerged as Judge Sanjeev Anand questioned the defence on an application Thursday in youth court. The 14-year-old, charged with arson, aggravated assault and attempted murder, appeared by video.

The accused cannot be named under the Youth Criminal Justice Act.

The Crown gave notice that, if the teen is convicted, it will seek to have her sentenced as an adult.

The defence applied for an assessment to find out whether the 14-year-old was not criminally responsible. Anand granted the request to assess whether, at the time of the alleged offence, the teen was suffering from a mental disorder.

Under questioning by Anand, court heard that the teen had been under the care of a nurse practitioner and had been diagnosed with a "psychotic disorder." She had also been admitted to hospital this past summer for emergency psychiatric care.

She has also been diagnosed with autism.

Witnesses previously told CBC what they saw unfold that day.

Grade 9 student Sophie Hubbard said she and her friend Lexxi Sparvier were leaving social studies class. Hubbard said she saw a girl pour liquid from a black container onto another girl and lift a hand toward the other girl's head, then saw the victim on fire in the hallway. Neither student saw what was used to ignite the fire.

"I just paused for five seconds and then I yelled, 'Fire!' and ran out with Sophie," Sparvier told reporters at the school yard a few days after the incident. "I'm still shaking a little."

Teachers were yelling for the victim to roll on the ground to help extinguish the fire and used fire extinguishers as the flames spread to part of a nearby wall, the two students said. The fire alarm went off as well, they added.

"I didn't believe it was real," Hubbard said.

The 15-year-old is still in hospital.