Israel's military carried out airstrikes in Rafah on Monday, residents said, hours after Israel told Palestinians to evacuate parts of the southern Gaza city where more than a million people uprooted by the war have been sheltering.
Fears are growing of a full-blown assault in Rafah, long threatened by Israel, against holdouts of Hamas as ceasefire talks in Cairo stall.
There was no immediate comment from Israel, which Hamas-affiliated Al-Aqsa TV said had targeted areas in eastern Rafah near neighbourhoods given evacuation orders.
Instructed by Arabic text messages, phone calls, and flyers to move to what the Israeli military called an "expanded humanitarian zone" 20 km away, some Palestinian families began trundling away under chilly spring rain.
Some piled children and possessions onto donkey carts, while others left by pick-up or on foot through muddy streets.
Senior Hamas official, Sami Abu Zuhri, said the evacuation order was a "dangerous escalation" that would have consequences.
Aid agencies have warned that the evacuation order will lead to an even worse humanitarian disaster in the crowded coastal enclave of 2.3 million people reeling from seven months of war.
"Forcing over a million displaced Palestinians from Rafah to evacuate without a safe destination is not only unlawful but would lead to catastrophic consequences," British charity ActionAid said.
Israel's military said it had urged residents of Rafah to evacuate in a "limited scope" operation. It gave no specific reasons nor did it say if offensive action might follow.