The wildebeest in the water was struggling.
"Croc's got it" said our guide.
The other wildebeest continued crossing – the odds of survival had just tipped in their favour.
The crocodile's plan was to tire out the wildebeest, and then to drown it. The wildebeest's only hope of escape was to drag the croc to the shore of the river, where the croc might release its grip.
According to the exif data, the struggle lasted almost 40 minutes. The wildebeest did get free, but, fatally, a long way from the shore. Probably the croc let go of the leg in order to move in for the kill.
The croc sprang, and missed. The exhausted wildebeest turned to face its tormentor. The croc sprang again, and took a death grip. It dragged the wildebeest under the water and, a few seconds later, the struggle was over. The crocodile swam away with its prize.
The rest of the herd finished crossing, and grazed peacefully on the other side.
In the Land Cruiser, we fell silent, even our experienced guide. Watching an animal lose its life after a long struggle arouses complex emotions, perhaps more so when the animal is a mammal and the predator a prehistoric reptile.
I was a long way from the action, so these images are heavily cropped.