Israeli troops battled Hamas in the heart of south Gaza’s biggest city and said they have surrounded house of one of the leaders as thousands of displaced civilians sought shelter near Egypt and in a desolate seaside area of the enclave, according to Reuters.

Gazans crammed into Rafah on the border with Egypt on the basis of Israeli leaflets and messages saying that they would be safe in the city. But they remained fearful after an Israeli strike on a house there killed 15 on Wednesday, according to health officials in Rafah.

Israel’s military said it advanced into the heart of southern Gaza’s largest city, Khan Younis, for the first time. Hamas wing, the al-Qassam Brigades, said combat is fierce.

Residents said Israeli bombing grew more intense, killing and wounding civilians, and tanks battled Palestinian fighters north and east of Khan Younis.