Woman fatally stabbed in Narre Warren, 15-year-old under police guard in hospital

A woman allegedly stabbed to death in Melbourne's south-east yesterday died trying to protect two other alleged victims.

A 15-year-old boy allegedly stabbed Channa Tep at the front door of her Narre Warren home before moving onto a toddler and then a 70-year-old woman in a bedroom.

The 70-year-old was able to call a friend for help just before she herself was attacked, but when the friend arrived, the tragedy had already unfolded.

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Police were called to the Springvalley Way home just after 1pm and when they arrived also found the teenager, who had sustained serious injuries, upstairs.

Ms Tep, 42, was airlifted to hospital with critical injuries but could not be saved.

The 70-year-old and toddler remain critical but stable and are in separate hospitals.

The 15-year-old boy remains at Dandenong Hospital under police guard after being arrested at the scene yesterday.

Homicide Squad detectives are investigating the incident and remained at the scene late into the evening last night.

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"Investigators are yet to determine the exact circumstances but are not looking for anyone else in relation to the incident," a Victoria Police spokesperson said.

Anyone with information that could assist police with their investigation is urged to contact Crime Stoppers on 1800 333 000.