As bushfires swept through parts of NSW on Wednesday, destroying two homes on the south coast, a group of boys ignored the total fire ban at the foot of the Blue Mountains.

Three boys have been charged with allegedly lighting a fire at the base of a cliff near Wattlecliffe Drive at Blaxland, around 4pm on Wednesday.

As video footage reveals, the boys were challenged by local residents whose properties were close by, and police were called.

Seven News reports some boys allegedly ran away while others attempted to smother the blaze – but it was too late.