Israeli troops advancing on three main routes

Israeli troops meanwhile appear to be advancing on three main routes, according to the Institute for the Study of War, a U.S. research group. One thrust came from Gaza's northeast corner. Another, south of Gaza City, cut across the territory, reaching the main north-south highway.

The third, from Gaza's northwest corner, has moved about 5 kilometers (3 miles) down the Mediterranean coast, reaching the outskirts of the Shati and Jabaliya refugee camps, on the edges of Gaza City. Airstrikes on Wednesday and Thursday destroyed apartment blocks in Jabaliya, but the number of dead and wounded remained unknown. Israel said the strikes killed militants and demolished Hamas tunnels.

Palestinian militants fired antitank missiles, set off explosive devices and hurled grenades at Israeli troops during an overnight battle, the Israeli military said Thursday. It said soldiers returned fire and called in artillery, as well as strikes from a helicopter and a naval ship. The report could not be independently confirmed.

Hundreds of thousands of Palestinians remain in the path of the fighting in northern Gaza, despite Israel's repeated calls for them to evacuate the region and head to the territory's south, which is also being bombarded. Casualties on both sides are expected to rise as Israeli troops advance toward the dense residential neighborhoods of Gaza City. Israeli officials say Hamas' military infrastructure, including tunnels, is concentrated in the city and accuse Hamas of hiding among civilians.