Media attended 76-year-old Andrew Cauchi's Toowoomba home as Joel Cauchi's victims continue to fight for their lives in hospital.

"This is so horrendous that I can't even explain it," he said.

"I love my son, I made myself a servant to my son when I found out he had a mental illness.

"I did everything because I love that boy."

When asked why his son may have targeted women during the attack, Cauchi's father said "he wanted a girlfriend and he's got no social skills".

"He was frustrated out of his brain," he said.

Mr Cauchi told reporters he was "extremely sorry" for the victims' families saying "I'm heartbroken for you."

The distressed father said there was "nothing I can do or say that will bring back the dead".

"To you he's a monster, to me he was a very sick boy."