Israeli forces launched their long-awaited storm of the main city in the southern Gaza Strip on Tuesday.
In what appeared to be the biggest ground assault since a truce collapsed last week, residents said Israeli tanks had entered the eastern parts of Khan Younis for the first time, crossing from the Israeli border fence and advancing west.
Some took up positions inside the town of Bani Suhaila on Khan Younis' eastern outskirts, while others continued further and were stationed on the edge of a Qatari-funded housing development called Hamad City, residents said.
After days of ordering residents to flee the area, Israeli forces dropped new leaflets on Tuesday with instructions to stay inside shelters during the assault.
"In the coming hours, the IDF (Israel Defence Forces) will begin launching an intensive attack on your area of residence to destroy the terrorist organization Hamas," said the leaflets, addressed to residents of six eastern and northern districts, amounting to around a quarter of Khan Younis.
"Don’t move out yet. For your safety, stay in the shelters and the hospitals where you are. Don’t get out. Going out is dangerous. You have been warned.”
The Israelis, who seized the northern half of Gaza last month before pausing for the week-long truce, say they are now extending their ground campaign to the rest of the enclave as they try to annihilate its Hamas rulers.
"We're moving ahead with the second stage now. A second stage that is going to be difficult militarily," government spokesperson Eylon Levy said.
Israel is open to "constructive feedback" on reducing harm to civilians as long as the advice is consistent with its aim of destroying Hamas, he said.
Reporting by Bassam Massoud and Ibrahim Abu Mustafa in Khan Younis, Gaza; Mohammed Salem and Arafat Barbakh in Rafah, Gaza; Maayan Lubell, Ari Rabinovich and Emily Rose in Jerusalem; Maggie Fick in BeirutWriting by Peter Graff, Editing by Timothy Heritage