Twelve hours of terror: how the Nova Scotia shooting rampage unfolded

New details have emerged in Canada's worst mass shooting, raising fresh questions about the attack and authorities' response

Emergency crews rushing to respond after reports of gunfire in a quiet Nova Scotia town were taken aback when they encountered thick clouds of smoke at the scene.

"Is there also a structure fire out this way?" one first responder asked his dispatcher. "We're seeing huge flames and smoke."