According to the National Sea Rescue Institute (NSRI), the 42-year old man was swimming about 50-meters from shore when he was attacked and then rescued by a bystander who pulled him to shore.
The NSRI spokesperson, Craig Lambinon, explained that when the medical team arrived they found that the man's left leg had been bit off just below the knee and the right leg bit off right above the knee.
Check out this amateur video that was shot and uploaded to YouTube showing the great white still lingering in the water just minutes after the victim was air-lifted to the hospital:
To read more on this attack that left the man in critical condition visit msnbc.