Paul McCartney attended the March for Our Lives in New York on Saturday, telling CNN the cause was important to him because he lost John Lennon to gun violence.

Wearing a shirt that said, “We can end gun violence,” the former Beatle told CNN’s Jason Carroll, he came to the march “just to support the people.”

“I don’t know” if we can end gun violence, McCartney said. “But this is what we can do, so I’m here to do it.”

“One of my best friends was killed in gun violence right around here,” McCartney said, “so it’s important to me.”

John Lennon, one of McCartney’s fellow Beatles, was killed in New York 37 years ago.

As Lennon and his wife, Yoko Ono, were walking in Manhattan one December night, a man fired five rounds into Lennon’s back, killing him.