Rescuers are rushing to reach survivors of Hurricane Katrina amid fears hundreds have been killed along the US Gulf Coast.Dozens of people are already known to have died but rising floodwaters in New Orleans have left hundreds more trapped in their homes and officials say the casualty list is certain to rise. Army engineers are conducting mass evacuations to help people flee the waters which have broken through defences. Martial law has been declared in some areas allowing police to impose curfews and stop widespread looting. Having slammed into Louisiana with winds in excess of 200 kilometers per hour,Katrina then swept across Mississippi, Alabama and Tennessee. Now it is past its peak, evidence of Katrina’s destructive power is becoming more apparent. Around a million people have been made homeless and officials say it may take weeks to restore power to homes left standing. The region remains on high alert for tornadoes. With estimates in excess of 25 billion dollars, insurers say the hurricane’s rampage could be the country’s most expensive natural disaster ever.