Tuesday marks a sad day in history that’s still seared in the minds of many.

Forty years ago, on Dec. 8, 1980, John Lennon was shot and killed outside his New York apartment. It was an event that shook the world and has had lasting repercussions, to this day. To mark the tragic anniversary, many of those who knew Lennon best are sharing remembrances of the music icon.

RELATED: Album John Lennon Signed For His Murderer To Go Up For Auction

Beatles bandmate and legend in his own right, Paul McCartney tweeted, “A sad sad day but remembering my friend John with the great joy he brought to the world. I will always be proud and happy to have known and worked with this incredible Scouser! X love Paul.”

Ringo Starr also remembered Lennon, saying, “Tuesday, 8 December 1980 we all had to say goodbye to John peace and love John. I’m asking Every music radio station in the world sometime today play Strawberry Fields Forever. Peace and love.”

RELATED: John Lennon’s Final Days Detailed In Upcoming BritBox Documentary ‘Lennon’s Last Weekend’

Lennon’s widow Yoko Ono added, “The death of a loved one is a hollowing experience,” Ono said. “After 40 years, Sean, Julian and I still miss him. ‘Imagine all the people living life in peace.'”

Meanwhile, Lennon’s two children, Sean and Julian, shared more staid tributes, with Sean posting a photo of him with his parents, and Julian tweeting out a photo of John captioned only, “As time goes by…”

RIP, John.