EL CAJON, Calif. — A moment-by-moment breakdown of events shown in two videos released Friday showing an El Cajon, California, police officer shooting and killing Alfred Olango, an unarmed black man.

One is surveillance video from a restaurant next to the shooting scene; the other is cellphone video shot by a restaurant employee from virtually the same angle.

— As the video begins, it shows only Olango, who appears unsteady as he walks through a parking lot.

— He stops suddenly and quickly backpedals when he sees a police officer, Richard Gonsalves, who walks toward him with his gun at his side in his left hand.

— Fifteen seconds later, a police cruiser enters the frame and Olango moves toward a parked white pickup truck. The cruiser is on his left, the pickup is behind him, and Gonsalves is in front of him.

— Five seconds later, Olango makes a quick move to his right and Gonsalves raises his gun.

— Olango then makes quick left-and-right movements and so does Gonsalves, who is about 10 feet away.

— Olango’s sister, who had called police, enters the frame behind Gonsalves. A woman, most likely the sister, is heard saying “officer don’t shoot him!” and “take your hands out!” At about the same time, the second officer, Josh McDaniel, gets out of the cruiser and moves toward Olango, though he remains much farther away than Gonsalves.

— Olango bends over and then raises his hands in front of him to chest level. Gonsalves shoots him four times in quick succession and Olango collapses to the ground. A woman shrieks loudly. It’s about 40 seconds after Olango first encounters Gonsalves.