Around 25 homes were evacuated during the incident.
Neighbours say it is the second time the property in County Down has been targeted in recent months.
The meeting was scheduled to discuss operational arrangements for the council’s new £35m leisure centre.
A woman and two men were inside the house at the time but there are no reports of any injuries.
Banbridge beat Annadale to win the men’s Kirk Cup final while Pegasus lift the women’s Ulster Shield with victory over Belfast Harlequins.