Police are investigating two suspected racist attacks at the same house in Castlewellan within the space of two days.
Around midnight yesterday a car was set alight outside a house in O'Donnell Park.
Police escorted two adults, two children and the family dog from their house as a precaution.
In the early hours of Tuesday, four men broke into the same house and assaulted a lady in her 40s.
Inspector Philip Quinn said: "This family has been frightened and upset by these two attacks - which had the potential to be much more serious.
"It is extremely fortunate that no-one was hurt in the latest incident as the fire could have spread to the house in which two young children were sleeping.
"The lady who was assaulted on Tuesday morning described three of her assailants as being dressed completely in black, while the fourth was in a white top and bottoms.
"Two were wearing monkey hats."
Police in Downpatrick have appealed for information.