A pipe bomb has exploded at the home of a prison officer in Holywood in County Down.
A number of items were taken away for examination
Several people suffered shock, but no one was injured in the incident at Ardmore Heights.
The explosion occurred shortly after midnight on Saturday.
Police said several people in the house saw a man approaching the window and managed to get out of the living room.
A device left on the windowsill exploded shortly afterwards.
A number of items were taken away for examination.
Police said they wanted to find out more about a silver car - possibly an Audi - seen in the area.
Another car, possibly a silver Vauxhall, was also seen nearby at the time.
Finlay Spratt of the Prison Officers' Association condemned the attack.
"These people continue to attack the homes of prison officers in the hope that they will change prison policy," he said.
"How can you describe people of that calibre who throw a bomb at a house where a man, his wife and family are living?
"We don't know who is responsible - we are just prison officers doing a job."
A Northern Ireland Office spokesman said it utterly condemned the bombing.
"Attacks like this only make us more determined in our resolve to see a complete and permanent end to all sorts of activities," he said.
Alliance Party councillor Susan O'Brien said she was concerned at the upsurge in paramilitary activity.