People are terrified of the power of the Great White shark, with the thought of this incredibly large and powerful shark swimming stealthily under a swimmer and then coming up with the mouth open and teeth ready to slash and bite being the stuff of horror movies, and the Jaws franchise did a lot to scare more people from sharks. However, there are a number of species of sharks that have attacked humans in the past; in some cases, experts say that the shark attack is because the shark mistakes the human to be similar to their prey and takes a bite to explore (the power of the bite can be pretty traumatic and can even cause death use to blood loss). In the current case, this lady was bitten by a small shark, a 2 foot long nurse shark which could not be shaken off and she had to be taken to the hospital with the shark still attached to her arm (link to article):
Paramedics in Boca Raton rushed a beachgoer to the hospital with a two-foot-long nurse shark clinging to her arm after efforts to disengage it failed. The South Florida Sun-Sentinel reported that the 23-year-old woman calmly walked up to a lifeguard station Sunday with the shark's jaws locked on her arm. Her boyfriend was helping hold the shark. Boca Raton Ocen Rescue told the newspaper that paramedics were called, but were unable to free her arm, even after the shark had died. So they loaded woman and shark into the ambulance and head for Boca Raton Regional Hospital. The Park Service says people swim near nurse sharks every day without realizing it and without incident. "Attacks" are rare and typically are the result of the shark being bothered with a hook, spear or hand.