Israel ordered civilians to leave four towns in the southern part of the Gaza Strip today, raising fears its attack against Hamas could spread to areas it had told people were safe, Reuters reports.

Leaflets dropped overnight from aircraft told civilians to leave the towns of Bani Shuhaila, Khuzaa, Abassan and Qarara, on the eastern edge of Khan Younis, the main southern city. The towns, collectively home to more than 100,000 people in peacetime, are now sheltering tens of thousands more who fled other areas.

“The acts of Hamas terrorist group require the defence forces to act against them in the areas of your residence,” the leaflets said. “For your safety, you need to evacuate your places of residence immediately and head to known shelters.” Residents said the area came under heavy bombardment overnight.

Israel has already ordered the evacuation of the entire northern half of Gaza before sending in its ground forces at the end of October. Long processions of people clutching just a few possessions have made their way south each day under the eyes of Israeli soldiers during six-hour “tactical pauses” to allow residents to leave.