The shark attacks on Thursday off South Padre Island have alarmed many beachgoers.

Two people were taken to hospital with bites, and two others were injured after an encounter with a shark.

The Texas Parks & Wildlife Department said all of the incidents involved the same shark. Videos show a crowd of people looking into the water as the shark swarms the area.

According to wildlife warden Captain Chris Dowdy, the last reported shark attack in the South Padre area was five years ago.

According to TPWD, encounters with sharks of this species are rare in Texas and sharks may mistake humans for food.

Sharks are a natural part of the ecosystem in Texas, and given that there are more than a billion sharks in the world's oceans, shark attacks are very rare.

The Florida Museum tracks shark attacks around the world with interactive maps.

According to the museum, there are 70 to 100 shark attacks each year, resulting in about five fatalities. The United States leads the world in the number of unprovoked bites, with most of them occurring in Florida.

“Shark attacks are a potential danger that everyone who frequently spends time in marine waters needs to be aware of, but it should be put in perspective. Bees, wasps and snakes are responsible for far more deaths each year. In the United States, there are up to 30 more deaths per year from lightning strikes than from shark attacks,” the museum's website states.

Why sharks attack

Most attacks occur near the shore or between sandbanks where sharks feed. Sometimes they get trapped at low tide.

The most common attack is called a “hit and run” attack, where a shark inflicts a single bite or cut on a human and does not return. Most of these incidents are due to confusion, as the shark is in the process of foraging for food.

Repeated attacks are rare but can include “bump and bite” attacks, where a shark circles a person and often bumps them before attacking, and “sneak” attacks, where a shark strikes without warning. Repeated attacks are usually more severe. In many of these cases, experts believe the attacks are the result of feeding or agnostic behavior rather than mistaken identity.

Due to the growing population and the increasing number of beaches, shark attacks have increased over the last century.

Prevent attacks

The Florida Museum recommends staying in groups in the water. Sharks are more likely to attack loners.

Here are a few more precautions beachgoers should take:

• Avoid being in the water at dusk or in the dark, as this is when sharks are most active.

• Do not enter the water if you have an open wound or are on your period.

• Do not wear shiny jewelry or watches as these may imitate the shine of fish scales.

• Contrasting colored swimsuits or tan lines may attract sharks. Sharks are colorblind but can see contrasting colors.

• Avoid swimming if there are signs of feeding activity; diving seabirds are a good indicator. According to TPWD, if you come across large schools of bait near shore, it could be a sign that a predator is nearby. You should stay calm and get out of the water to wait for the animal to pass.

• Avoid excessive spraying.

• Do not bring pets into the water.

• Be careful in areas between sandbars or near steep drop-offs as sharks often congregate there.

If you are attacked by a shark, it is better to be aggressive than passive. Punching the shark on the nose can temporarily stop the attack so you can get out of the water. You can also scratch its eyes or gill openings with your claws.

Click here for tips on how to avoid shark attacks while diving.

Shark attacks in Texas

According to the museum, there have been fewer than 50 documented unprovoked shark attacks in Texas since 1911.

In search of sharks

Ocearch is a non-profit organization that studies marine life for conservation. Currently, Ocearch is tracking 437 tagged marine animals to understand their behavior. You can track these animals here.