Police are appealing for witnesses after would-be arsonists threw a petrol bomb through the window of a house in Bolton.
They then threw a lit petrol bomb through the broken window but it failed to ignite.
A second petrol bomb was recovered from the scene.
Detective Inspector Chris Walker, said: “The occupants are obviously deeply concerned by what has happened and are working with us as we try and establish who is behind this attack.
“I want to reassure the public that we do not believe this was a random incident or that there is a threat to the wider public.
“Clearly, the use of petrol bombs is a grave offence and had it ignited the consequences could have been catastrophic.
“If anyone knows anything about the people responsible or saw a black car driving around the area in the early hours of this morning, please get in touch.”
Anyone with information is asked to call police on 0161 856 5740, or Crimestoppers, anonymously, on 0800 555 111.