GAZA CITY, Palestine  At least 15 Palestinians were killed as the Israeli army stepped up bombardment of the Gaza Strip on Monday, according to medical sources. Two Palestinians lost their lives when Israeli forces bombed the refugee camp of Jabalia in northern Gaza, one source said. Five people were also killed and 10 others injured in an airstrike on a home west of Gaza City, the source added. Women and children were among the victims, the source said, without giving an exact figure. Two