Mark Barden, whose son Daniel was killed in 2012 by a gunman at Sandy Hook Elementary School in Newtown, Conn., posted an open letter on Facebook to Richard Martinez, whose son Chris was killed Friday in the rampage in Santa Barbara, Calif. In the letter posted Tuesday, Barden welcomes Martinez to the “extended family” of parents who have lost children to gun violence and offers support for Martinez’s call for legislative action in the wake of the Santa Barbara shootings.

Read the full letter:

The Washington Post’s Eli Saslow profiled Mark and Jackie Barden in 2013.