Two teenage boys have been charged with murder and attempted murder after a woman was killed at her home in north Brisbane on Boxing Day.
Emma Lovell, 41, was fatally stabbed in the chest after allegedly disturbing the offenders inside her North Lakes home at about 11.30pm on Monday night, police said.
Her husband Lee Lovell, 43, was stabbed in the back.
Superintendent John Hallam said the couple were "trying to defend their home".
He said a 17-year-old boy from Zillmere and a 17-year-old boy from Holland Park fled and were tracked down by the dog squad, and they and two other teenagers were arrested in the early hours of Tuesday morning.
Police are still questioning the other two teenagers, a 17-year-old and 16-year-old.
He said police had had "prior contact" with all four teenagers.
The mother-of-two died at hospital.
It is understood Queensland Ambulance Service medical director Stephen Rashford and another officer performed an emergency procedure known as a thoracotomy at the scene.
The lawn was still strewn with medical debris the next day.
"We were confronted with a horrific scene. Paramedics did all they possibly could. Unfortunately the lady passed away when she attended the hospital," Superintendent Hallam said.
He said the community is in mourning.
"I still struggle to understand why these types of violent crimes occur," he said.
Superintendent Hallam said youth crime was a "whole community problem".
"This isn't a policing problem. We can't arrest our way out of this. It's a whole community challenge."
Jay Balhatchet, who lives across the street from the family, said neighbours rushed over to find the father already on the phone to emergency services.
"When the guys ran off, he was already on the phone and trying to help his wife," he said.
Mr Balhatchet said he watched as paramedics tried to save Ms Lovell for 15 to 20 minutes on the front lawn.
Police are urging anyone from the North Lakes area with information, CCTV footage or dash cam footage, to come forward.
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