The idea that people behave like animals during natural disasters may summon up a vision of screaming barbarians, looting, stealing, fighting against the odds for their lives and ignoring moral values. However, the natural laws according to life on Earth require all living beings to work towards the survival of their species, and ultimately, people may behave like animals when a disaster strikes, but that behavior isn't necessarily lacking in altruism or kindness.
Humans have inbuilt instincts which are likely to surface when faced with a challenging situation which provokes fear. People may discover that they behave in ways they never imagined possible until they undergo such an experience. While some may adopt the attitude of saving themselves above all others, the majority of people are programmed by mother nature to work as a team, and keep up strength by preserving numbers.
When the twin towers exploded in September, 2001, people clamoured for their lives, but they also tried to help one another. They reached out to loved ones, and major rescue attempts were made. Other disasters, natural or made made, provoke a similar response in people. It makes no difference if a disaster which humans aren't deemed responsible for befalls a nation, or an attack by an individual on another occurs. Our main reaction, apart from horror, is to make the problem stop and help injured parties.
Like-wise animals work as a team, either staying close in a herd to warn each other quickly if danger approaches, or taking turns to look out for potential problems they then yell along the grapevine to other members of their species.
At the same time, there is often altruistic behaviour, which can be witnessed in both animals and people, which spreads across species. People may help animals during a disaster, and animals may even help members of different animal species. It's not rare for mother dogs to adopt baby animals from a different species, or for animals to let all other animals know if an emergency is occurring.
In many ways we are far more sophisticated than animals. We seem capable of having a higher level of morality and spirituality than most, but when it comes to natural disasters we are prone to behaving in a similar manner to members of the animal kingdom. In this way, we are not so dissimilar to animals after-all, despite our perceived intelligence, but the behaviour we share is more likely to be positive and rewarding, than beastly and aggressive in times of dire need.