(GAZA CITY, Gaza Strip, AP) — A U.N. aid agency says some 10,000 Gazans have sought shelter in U.N.-run schools after the Israeli military dropped leaflets on the territory warning residents of certain areas to evacuate their homes.

Adnan Abu Hassna, spokesman for the U.N. Relief and Works Agency, said Wednesday that 12 schools are providing shelter.

He says the influx began Tuesday evening, after Israel dropped the leaflets over Gaza. The Israeli military has not given a reason for the warning, but many here fear it is the prelude to a possible ground offensive.

Israeli ground troops last entered Gaza four years ago, during a previous offensive against Gaza’s Hamas rulers, leaving a widespread devastation.

U.N. compounds are seen as safer than ordinary homes, though some were also hit in 2009.