21 Israeli troops are killed in the deadliest attack on the military since the Gaza offensive began

Palestinian militants carried out the deadliest single attack on Israeli forces in Gaza since the Hamas raid that triggered the war, killing 21 soldiers, the military said Tuesday, a significant setback that could add to mounting calls for a cease-fire.

Hours later, the military announced that ground forces had encircled the southern city of Khan Younis, Gaza’s second largest, and thick, black smoke could be seen rising over the city as thousands of Palestinians fled south. Witnesses said Israeli tanks and troops had also moved into Muwasi, a nearby coastal area that the military had previously declared a safe zone for Palestinians.