On Dec. 14, 2012, Mark Barden had no idea he was spending the last morning hours with his 7-year-old son, Daniel. The father remembers how Daniel was asking to hold hands as they walked to the bus stop at the end of the driveway.
At 9:30 a.m. on that same day, a gunman opened fire inside Sandy Hook Elementary School. Daniel, 19 other first-graders and six educators were dead.
Daniel was described as compassionate boy, known for sitting next to isolated classmates and moving worms from the sidewalk to the cool grass "where they had families they loved and they needed to be together," as he told his dad.
On the sixth anniversary of the mass shooting, Mark still can't help but retrace every moment he spent with his son: "That's one part of this journey that I have to reckon with."