Palestinians scrambled to flee northern Gaza on Saturday after the Israeli military ordered nearly half the population to evacuate south and carried out limited ground forays ahead of an expected land offensive a week after Hamas’ bloody, wide-ranging attack into Israel.

Israel renewed calls on social media and in leaflets dropped from the air for some 1 million Gaza residents to move south, while Hamas urged people to stay in their homes. The U.N. and aid groups have said such a rapid exodus would cause untold human suffering, with hospital patients and others unable to relocate.

Families in cars, trucks and donkey carts packed with possessions crowded a main road heading away from Gaza City as Israeli airstrikes continued to hammer the small, besieged territory. Palestinian witnesses said Israel struck cars rushing south, and Hamas said the strikes killed more than 70 people.