A four-month-old baby has been badly injured in a shocking meat cleaver attack, allegedly at the hands of his own grandmother.

The little boy was slashed across the face repeatedly as he slept in a cot in a Brisbane home.

He suffered cuts to his forehead, cheek and neck, with blood transfusions required on the way to Lady Cilento Children’s Hospital just to keep him alive.

According to 7 News, the crime scene was so horrific it brought seasoned police officers and paramedics to tears.

Camera Icon The white-haired grandmother was taken into custody at the home. Credit: 7 News

“It was distressing to see such injuries to such a small child,” Insp Daniel Bragg said.

“This is the worst-case scenario.”

The four-month-old and his mother were visiting the home from Sydney when the attack happened on Tuesday morning.

The little boy’s mother was woken just after 6am by the sound of her child crying in his cot.

Play Video A four-month-old boy is in a critical condition after being stabbed in the face. The West Australian Video A four-month-old boy is in a critical condition after being stabbed in the face.

“The mother found the child in a distressed state with injuries to his face,” Insp Bragg said.

“She’s clearly distraught over what’s occurred. She’s provided police with all the assistance she could.”

The infant boy's grandmother, who is a former school teacher, was led out of her home in a forensic suit with paper bags on her hands at The Gap, in Brisbane's western suburbs.

“It just makes me feel ill,” witness Chris Dixon told 7 News.

“It’s horrible. I can’t imagine what would make somebody do that.”

Camera Icon Police at the Brisbane home. Credit: 7 News

The 64-year-old grandmother's mental health had been declining, but police have been told she's never shown signs of violence.

Sources have told Seven News she appeared dazed immediately after the atrocity and that she has little memory of it since.

The four-month-old underwent emergency surgery on Tuesday and remains in a serious condition with his mother by his side.

The 64-year-old grandmother has been charged with attempted murder and will appear in court on Wednesday.