The RUC have recovered two pieces of copper piping that they believe to be part of the crude pipe bombs that exploded in Co Down today, a spokeswoman said.
Police found the piping during their investigations of attacks on two houses in the Loughside area of Ballynahinch this morning.
The six occupants of one of the houses were uninjured when a window was blown in by the explosion.
Another family a few doors away were also in their house when the attack happened but their home was not damaged.
Mr Mick Murphy, Sinn Féin assembly member for the area, blamed the attack on loyalists, adding they were stepping up their campaign to intimidate Catholics across Northern Ireland.
"The silence coming from Unionism is of great concern and the attitude of the RUC to such attacks also highlights the need for the creation of a new policing service," he said.
The RUC are continuing their investigation.
Additional reporting PA