Substantial damage was caused after a device exploded at the door of a house at Kinnegar Road, Finaghy, in south Belfast,
It is believed that the object was left at the front door of the house shortly after midnight. There are no reports of any injuries at this time.
Two men wearing all-black clothing were seen heading along Benmore Drive toward Mount Aboo Park following the incident.
Officers remain in the area to carry out further enquiries and anyone with any information is asked to call police at Lisburn Road on 101, quoting reference number 12 22/07/22. A report can also be submitted online using the non-emergency reporting form via http://www.psni.police.uk/