A teenager was stabbed by his father while trying to shield his mother in a frenzied attack in Brisbane's south.

The 37-year-old mother was stabbed repeatedly in the head, neck, chest and arms by her ex-partner, Saliceni Kaladrou.

Their 18-year-old son bravely stepped in and fought his father off, but suffered multiple stab wounds to his arms and hands.

An 18-year-old (pictured) is being praised a hero after he fought off his father from allegedly stabbing his mother Monday morning

Saliceni Kaladrou (pictured with his three youngest children) allegedly stabbed his ex-partner before then stabbing his 18-year-old son

Neighbour's aren't surprised of the heroic actions from the 18-year-old, saying that's just the type of person he is (pictured his parents)

Neighbours of the Brisbane family told 9 News the bravery of the 18-year-old did not surprise them.

'I wouldn't doubt that for a second that's the kind of person he is,' neighbour Alan Walters said.

'He used to come over and clean my gutters and just out of the goodness of his heart.'

The mother and son were rushed to Princess Alexandra Hospital while the three younger children were taken by police and are staying with relatives.

The woman is in a stable condition.

Kaladrou (left) allegedly fled the scene before crashing his car into a parked truck in Brisbane's south

The mother and Kaladrou's three young children (two pictured) were taken from the house and are now in the care of relatives

Kaladrou crashed his car (pictured) not far from alleged stabbing before 4am Monday morning

Kaladrou, 46, allegedly fled the scene, which occurred at a home on Collina Crescent about 4am Monday morning before he crashed his car into the back of a parked semi-trailer, instantly dying.

The truck driver was asleep at the time and had parked at Wacol, south of Brisbane.

The national domestic violence helpline is 1800 737 732.

It is believed Kaladrou died instantly when he crashed into the back of the parked truck