GAZA CITY (AFP) - Children make up a quarter of the more than 600 Palestinians killed in Israel's war on the Hamas rulers of Gaza and aid workers say those who survive will suffer lifelong psychological scars. Whole families have been killed in their shelled homes or in cars trying to get away from the fighting. By Tuesday afternoon, the number of children killed since Operation Cast Lead was launched on December 27 stood around 160, according to Gaza emergency services. "The bottom line is if you're operating heavy weaponry in a very densely populated area, people who have nothing to do with the conflict will die. Sadly, this includes kids," said Benedict Dempsey of the Save the Children group. The impoverished Gaza Strip is one of the most overcrowded corners of the Earth, where children make up 56pc of the 1.5 million population. Aid workers believe just about every Gaza child has been traumatised by the incessant bombardment which Israel says targets the Islamist rulers and aims to silence the daily rocket fire aimed at the Jewish state. "They can't play, they can't sleep, they can't go to school. They're traumatised," said Dempsey. Civilians have virtually nowhere to hide. The borders are sealed off under an 18-month-old Israeli embargo, and schools, where many families have sought refuge, are not safe. On Tuesday, an Israeli strike killed at least 40 people who had taken refuge inside a UN-run school, medics said. Five people were killed in strikes on two others schools, they said. Children are particularly vulnerable. A child trapped in the rubble of a bombarded building has fewer chances of surviving than a healthy adult, according to aid workers who highlight that Gaza children are already in a weakened state. "Before this began, there were already 50,000 malnourished children in Gaza. There is no way of knowing how many there are now, but we are very concerned the number is going to rise," said Dempsey. Food stocks are dangerously low, many families keep washing to a minimum to save water for drinking. Power is out in virtually all of Gaza and many windows have been blown out, leaving residents shivering in the cold nights. "Children are terribly frightened," said Dempsey. "This will live with them for the rest of their lives. It's the sort of experience they'll never forget. They just don't understand what's happening."