Israeli air strikes in the heart of Gaza City have flattened three buildings and killed at least 26 people, making it the deadliest single attack since heavy fighting broke out between Israel and the territory’s militant Hamas rulers nearly a week ago.The Gaza health ministry said 10 women and eight children were among those killed in Sunday’s attack, with another 50 people injured.Rescuers raced to pull survivors and bodies from the rubble following the assault.