There are grave fears for three young children found inside a burning property in Melbourne about 9.30pm on Sunday night.

The children – aged 21 months, three and five – were found when firefighters entered the home in Fergus Court, Sydenham, in Melbourne’s north-west.

Smoke and flames were billowing through the roof of the single-storey suburban property when about 30 firefighters arrived.

The children were rescued and treated by paramedics outside before being rushed to hospital with life-threatening injuries.

Police are investigating whether a parent or parents were home at the time of the blaze, according to media reports.

It’s not yet known what sparked the fire.

Neighbours described a horrific scene as the children were worked on by paramedics outside the home.