A MAN who stabbed a 37-year-old woman and her son in a home in Brisbane's south has died in a crash after fleeing the scene.

Police said the man entered a home on Collina Cr at Forest Lake about 3.30am, where he stabbed a woman and her son, 18, before leaving the scene in a car.

The two victims suffered multiple stab wounds.

The son suffered lacerations to his hands while his mother suffered serious but non-life threatening injuries.

Both are in the PA Hospital in a stable condition.

Moments later, a man was killed in a crash on Federation St at Wacol about 3.45am.

It is understood the vehicle he was driving crashed into a parked semi-trailer.

He was declared dead at the scene.

Police have since confirmed he was the attacker at the Forest Lake home.

"We have identified the person who did the stabbing and that man has been involved in a fatal crash," police said.

Police said the offender had been in a relationship with the woman.

It was also confirmed that there were children in the Forest Lake home at the time of the stabbing.

Police said there was an 18-year-old and three younger children, who were being cared for by relatives.

Formation St remained closed at 6.30am. Diversions were in place.