Minneapolis, Minnesota (CNN) -- For 13-year-old Arrianna Merritt, the words mother and hero go hand in hand. Three years ago Sunday Arrianna watched her mother Kim Dahl drive a school bus loaded with children across the Mississippi River when the bridge began to buckle up and down. Thirteen people were killed in the bridge collapse in Minneapolis, Minnesota. What Arrianna remembers most was the choice her mother made that day after the bus became tilted upward on a steep incline. "Either you let us free fall -- or you hold that brake to the ground and you stay where you are." Dahl held the brake with her foot until she could reach for the parking brake.
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Mom helped save 52 kids, eight adults after '07 Minneapolis bridge collapse
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Ordeal of surviving the collapse of 1,900-foot bridge changed her family forever
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Mother, daughter bonded tightly, returning to the bridge site 3 years later
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Mother's health issues from the collapse forced daughter "to be a grownup"
And while @placeholder no longer has therapy sessions of her own, occasionally she still struggles.