Ottawa, Oct 29 (IANS): A teenager pleaded guilty to the murder of four persons and wounding seven others in a mass shooting at a high school and in a home in western Canada earlier this year.

The teenager, whose name could not be released under the Youth Criminal Justice Act, on Friday entered guilty pleas to first-degree murder in the shooting deaths of two teachers at the La Loche school in Saskatchewan on January 22, the Toronto Star reported.

He pleaded guilty to second-degree murder in the deaths of two teenage brothers at a nearby house in the remote aboriginal Dene community.

He also pleaded guilty to attempted murder for wounding seven others at the school.

"I don't need to tell everyone these charges are very serious, very tragic -- tragic for everyone involved in that region," said provincial court Judge Janet McIvor.

McIvor said the courts still need to determine if the teenager, now 18, should be sentenced as a youth or an adult. The maximum youth sentence for first-degree murder is 10 years in custody.

An adult receives an automatic life sentence and, under a new provision for multiple murders, can receive consecutive periods of parole ineligibility of up to 25 years for each victim.

"It's very important that his hearing be held in the community where these events happened," said the judge.

At the time of the shooting, the teenager's friends described him as the black sheep of his family and a victim of bullying at school. One person said the teenager was often teased about his large ears.

Another student kept a screenshot of a chilling exchange that took place on social media just before the shooting.

The police, who responded to panicked calls from staff and students, said the shooter was inside the school for about eight minutes. The building's main doors had been blasted with holes. Some students fled; others hid in fear.

Substitute teacher Charlene Klyne, 56, was sitting at a desk when she saw the teen raise a gun at her through the window of her classroom door.

"All of a sudden everything was hurting and everything went red because the pellets went into my eyes," Klyne said in an earlier interview.

Klyne, who lost her sight, said teacher's aide Marie Janvier was in the room with her and was killed when she ran to get help. Janvier, 21, had graduated from the same school two years earlier and it was her first year working there as an aide.

Teacher Adam Wood of Uxbridge, Ontario, had also just started his job at the beginning of the school year. The 35-year-old was also shot and died of his wounds in hospital, the Toronto Star reported.

Shortly after the shooting, officers were called to another crime scene in a nearby home where two brothers -- Drayden Fontaine, 13, and Dayne Fontaine, 17 -- were found dead.