The 9/11 images that still haunt journalists who witnessed the tragedy 25 years later

On Sept. 11, 2001, Karen Matthews was inside her Manhattan apartment preparing her three-year-old daughter for preschool when an unfamiliar, thunderous boom echoed outside.

Clutching her young child, she stepped onto the street. Onlookers were gazing upward at a gaping hole in the World Trade Center’s north tower, where dark smoke poured into the sky only a short distance from her residence.