 Residents of Gaza City say columns of Israeli tanks are advancing into the center from different directions. Residents in several districts of Gaza City received evacuation orders from the Israeli army on Sunday evening. But in other districts where there have been Israeli strikes, some people say they didn't receive any warning. Many have said they no longer know where to go. Emergency services in Gaza say they believe dozens of people may have been killed but haven't been able to reach them so far because of the fighting. The Israeli army says it launched this new operation