JUDY WOODRUFF, CNN ANCHOR: British authorities have not announced what caused an explosion Wednesday in Belfast. But the blast is raising new fears that a cease-fire in Northern Ireland may not hold. CNN's Nic Robertson reports.</s>NIC ROBERTSON, CNN CORRESPONDENT (voice-over): Police moved in quickly to seal off the area around the blast. It ripped through the roof of a garden shed in this staunchly Catholic neighborhood, injuring a 59-year-old man and his 29-year-old son. Now in hospital recovering, the pair will be questioned by police, who say their testimony and forensic evidence will be critical in establishing the cause of the blast. (on camera): Even though this blast did little damage, its impact on Northern Ireland has ban heightened by growing tensions within the provinces' paramilitaries. (voice-over): Barely 12 hours before this blast, a Protestant paramilitary group, the Ulster Freedom Fighters, or UFF, declared they now reserve the right to shoot anyone attacking Protestant homes, effectively ending their commitment to a 1994 cease-fire. The move does not have the backing of all Protestant terror groups, but by implication, threatens Northern Ireland's fragile peace.</s>PETER MANDELSON, BRITISH N. IRELAND SECRETARY: Anyone who thinks that they can go around threatening violence, or stirring up trouble, particularly as we enter the marching season, and think they can get away with it, my answer to them is simple: You will not get away with it.</s>ROBERTSON: Only a few days ago, a bomb was found on the grounds of Mandelson's official Northern Ireland home, a sign politicians here say that the terror groups are still active. This latest blast only confirms that threat of a return to violence is growing. Nic Robertson, CNN, Belfast, Northern Ireland.
Explosion in Northern Ireland Puts Cease-Fire in Doubt