On the night of December 8, 1980, ABC broadcaster Howard Cosell interrupted Monday Night Football to announce that John Lennon had been murdered outside of his apartment in Manhattan. I was in bed in a school dormitory when the news came over the radio the next morning. I thought, “Who would want to kill John Lennon?”

Lennon and his wife, Yoko Ono, had returned late in the evening from a recording session and were walking through the archway of their historic German Renaissance building, nicknamed The Dakota, when a gunman shouted out Lennon’s name. Before the man who had written A Ticket to Ride and All You Need is Love could turn around, Mark David Chapman had fired four hollow-point bullets from a .38 revolver into his back. Lennon climbed several steps to The Dakota’s reception area, saying “I’m shot! I’m shot!” He slumped to the floor and the cassette tapes in his hand, produced during the afternoon’s recording session at the Record Plant studio, fell from his grip and clattered on the hard floor.

Concierge Jay Hastings began to make a tourniquet, but seeing it was hopeless removed Lennon’s blood-drenched glasses and lay his own jacket over John’s body. Dakota doorman Jose Pedormo rushed out to Chapman, saying, “Do you know what you have done?”

The deranged assassin, who stood calmly waiting the arrival of the police, replied, “I just shot John Lennon.”
Police officers at the scene placed Lennon in the backseat of their squad car and took him directly to Roosevelt Hospital rather than wait for an ambulance. When Lennon was pronounced dead a little after 11 p.m., hospital staff noticed the Beatles song All My Loving was playing on the radio.

Six days later, at Ono’s request, millions observed ten minutes of silence and every radio station in New York City went off the air.
Beatle George Harrison told friends: “I just wanted to be in a band. Here we are, 20 years later, and some whack job has shot my mate. I just wanted to play guitar in a band.”

He blew his mind out in a car
He didn’t notice that the lights had changed
A crowd of people stood and stared
They’d seen his face before
Nobody was really sure if he was from the House of Lords

— A Day in the Life (1967)

Read more in the book, The Other Side of John Lennon.