Virginia ? Two years after they were wounded by a gunman who sprayed bullets through their German class at Virginia Tech, Katelyn Carney and Derek O’Dell helped the campus mark the second anniversary of the worst mass shooting in modern U.S. history.

Carney, who graduated in December, returned to run a 3.2-mile race Thursday to honor the 32 people killed April 16, 2007, by student Seung Hui-Cho, who also took his own life. She and O’Dell worked together to bar the door to their classroom so Cho couldn’t get back in.

“This is where it matters,” she said as she and a friend prepared to run.

O’Dell, who walked the race course, called the experience bittersweet.

“We’re celebrating their lives, but remembering, too,” he said. “It’s difficult, but I think it’s important.”

Also Thursday, the last two victims’ families who hadn’t agreed to an $11 million settlement sued the state and school.