While Hillary Clinton was in Boulder for a grassroots organizing event Tuesday, she also met with survivors of gun violence and their family members.

Two of the nation's major mass shootings were in Colorado -- the Columbine High School shooting in 1999 and the Aurora shooting in a movie theater in 2011. A Clinton campaign official said family members of those who perished in both of those massacres, as well as a woman whose sister was killed in the Sandy Hook Elementary School shooting attended the meeting.

Clinton listened to their stories and promised to fight for measures to prevent gun violence, including comprehensive background checks. 

She reiterated that message in her remarks at the Boulder Theater, where more than 1,000 people turned out to see her speak.

"I'm going to be talking about this and fighting for this and standing up for this now through the primaries and caucuses and into the general election," she said, "because I want this to be a voting issue."

The meeting in Boulder follows a similar one she had in Memphis last week, when she met with family members of Darrius Stewart. Earlier this month, in Chicago, Clinton met with the mothers of Eric Garner and Dontre Hamilton, and other mothers whose children died as the victims of gun violence.