“How did we not stop this after Columbine? After Sandy Hook?” Samuel Zeif, a Marjory Stoneman Douglas High School shooting survivor, asked Wednesday at the White House.

Zeif joined other survivors, parents, and educators who pleaded with President Donald Trump to protect America’s schools from mass violence like the kind that left 17 dead in Parkland, Florida, last week.

The emotional session, which included the president, Vice President Mike Pence, and Education Secretary Betsy DeVos, brought together people with ties to high-profile school shootings, including those from Parkland, Sandy Hook Elementary School in 2012, and Columbine High School in 1999.

Zeif, an 18-year-old senior at Stoneman Douglas, is one of the newest members of this sorrowful club. He recounted the moments last Wednesday when he texted his parents and siblings that he might never see them again — including his younger brother, who was also in the building.

Zeif’s wrenching exchange with his 14-year-old brother during the shooting was widely shared online afterward. “No brothers or sisters or family members or anyone should ever have to share those texts with anyone,” Zeif said Wednesday through tears.

He and his brother survived, but one of Zeif’s best friends was killed. “That’s why I’m here,” he said. “I lost my best friend; he was practically a brother. I’m here to use my voice because I know he can’t.”

"I lost a best friend. ... I don't understand why I can can still go in a store and buy a weapon of war" Sam Zeif was on the second floor of the Parkland, Florida, school where 17 people died after a mass shooting. https://t.co/3j4r9cQ3Ko https://t.co/uTvMrOqvYC — CNN (@CNN) February 21, 2018

Zeif was one of the attendees at the president’s listening session to speak most openly about specific gun control measures. “I don’t understand. I turned 18 the day after, woke up to the news that my best friend was gone,” he said. “And I don’t understand why I could still go in a store and buy a weapon of war.”

“How is it that easy to buy this type of weapon? How did we not stop this after Columbine? After Sandy Hook?” Zeif said, as he put his hand on the shoulders of Nicole Hockley, whose son Dylan died at Sandy Hook. “It’s still happening.”

Zeif is among many outspoken Parkland survivors who are demanding change after the shooting last week. Their impassioned speeches and activism on social media has helped spark this renewed push for solutions to America’s mass shooting epidemic. Students, survivors, and other activists are organizing a March for Our Lives in Washington, DC, and other cities on March 24.

On Wednesday, on the one-week anniversary of the deadly shooting, Parkland survivors rallied in Florida’s state capital in Tallahassee to push for gun reforms, and about 1,000 students in nearby schools marched to Marjory Stoneman Douglas High School to protest and honor the victims. The movement, which is still building, and the students who continue to speak out are signs that after this mass shooting, what’s considered the status quo may change.