He was there during a food drop. There was a famine. he hitched a ride on a plane which stopped there for only 30 minutes to give out food.
While mothers and fathers were receiving the food from the plane, the children were by themselves. The photographer, kevin carter, saw this suffering child with a vulture behind it. He took the picture then chased the vulture away.
Minutes later, after the food had been passed out, he got on the plane and left.
He was a good man. He spent his life risking his own safety taking pictures of horrible things, to expose them to the world. Mostly his work was regarding the brutality of apartheid in south africa, such as this picture, a public execution by "necklacing" (carried out by forcing a rubber tire filled with petrol, around a victim's chest and arms, and setting it on fire):
His good friend, Ken Oosterbroek, also photographer apart of the same group (Bang-Bang club), which explosed the brutality in south africa, was killed taking photo's, which also led to Kevin's suicide. In his suicide note (three months after taking the vulture picture):
I am haunted by the vivid memories of killings and corpses and anger and pain ... of starving or wounded children, of trigger-happy madmen, often police, of killer executioners...I have gone to join Ken if I am that lucky.
He took these pictures for a good cause, not for fame and profit.