Kait Hinckley’s sister was killed while shopping for Valentine’s Day cards. Kristin, who was 15, was one of five victims of a shooting that happened in Trolley Square in Utah in 2007, KSL reports.

Hinckley recently shared her story with the Bloomberg campaign in a video in which she explains that her mom was also permanently disabled because of the shooting.

The 18-year-old gunman was killed during a shootout with police.

“It makes me so angry that someone could do that,” Hinckley goes on to say in the video.

The video was filmed as part of Mike Bloomberg’s presidential campaign promise to focus on revising gun safety laws in Utah and around the country.

Read more about Mike Bloomberg’s campaign plans for addressing gun safety in Utah and other American cities here.