A 43-year-old man accused of dousing his three children in petrol before setting one of them on fire has appeared in a Perth court.

Edward John Herbert appeared in the Perth Magistrates Court on one count of aggravated grievous bodily harm and two counts of attempted grievous bodily harm.

He was shirtless, incoherent and humming to himself, and was held up by two officers and unable to respond to the charges due to his mental state.

Hebert was charged after police were called to a disturbance in Holbeck Street in Doubleview shortly after midnight on Saturday morning.

Neighbours said they had heard a woman screaming "help, he's set the kids on fire".

An off-duty officer living on the street entered the house to find the man's three-year-old daughter on fire, before placing the girl in a bath.

Neighbours also said they helped restrain the father, who was brandishing a knife.

It is believed the girl had been lying in a cot when she was doused with flammable liquid.

She suffered extensive burns and remains in a critical but stable condition at Princess Margaret Hospital (PMH).

Her seven-year-old sister and a six-year-old brother also allegedly had lighter fluid poured on them.

The sister also suffered burns and is in a stable condition in PMH, while police said the boy was being looked after by relatives.

Herbert was remanded in custody and will reappear in court on Tuesday.