Rescuers search rubble
After the collapse of the World Trade Center more than 5,000 people were declared missing. Rescuers worked around the clock, carefully searching the ruins in the hope of finding people alive. Five survivors were found in the first 24 hours.
Often people can survive for many days in collapsed buildings, but the weight of the floors and scale of the disaster made this possibility unlikely in New York. Initial hopes that many people would be discovered alive soon began to fade.