“Modern-day musket my ass,” tweeted David Hogg.
Amanda Chase is facing backlash over the ad, which she said was a mistake.
Survivors of the Parkland shooting are urging the government to declare a national emergency on gun violence.
Parkland shooting survivor David Hogg called on former Vice President Joe Biden and others to attend the forum, set for Oct. 2 in Las Vegas.
But the 19-year-old gun control advocate said these threats haven't dissuaded him from his activism. "I’m not going to stop," he said.
“I love you forever and miss you every second of every day,” tweeted the father of slain 14-year-old Jaime Guttenberg.
“The idea anybody could take joy in the destruction of young kids is absolutely outrageous to me," she said of the Covington Catholic students.
The gun control activist announced his plans several months after Fox News' Laura Ingraham mocked him for not getting into a few universities.
President Donald Trump's bonkers "stable genius" claim took sixth spot in Yale Law School librarian Fred Shapiro's annual list.
Archbishop Desmond Tutu awarded the March for Our Lives organizers the 2018 International Children's Peace Prize.