GAZA CITY (AFP) - A seven-year-old girl in Gaza was killed on Thursday when she was struck by a shell fired from an Israeli tank, Palestinian witnesses said. Hyam Ayash died and four other people were wounded, one of them seriously, when the tank fired a mortar towards a target near Bureij refugee camp in the central Gaza Strip, the witnesses said. An Israeli military spokeswoman told AFP there was an exchange of fire in the sector, without confirming or denying that a tank had been involved.