Gaza has come under renewed bombardment from Israel, as agreement on a ceasefire to end a week of violence remains elusive.
At least 20 Palestinians were reported to have been killed on Tuesday. Two Israelis - a soldier and a civilian - were killed in rocket strikes.
Earlier, Egyptian and Palestinian officials said a ceasefire would shortly be announced at talks in Cairo.
But Israel has said a deal is not yet done.
And late on Tuesday, a senior Hamas official, Izzat Risheq, said a deal might not be reached until the morning.
The Israeli military said its renewed artillery fire had targeted "two terror operatives" in the central Gaza Strip.
Earlier, it had asked residents in villages around Gaza City to move to central areas for their own safety. Those killed in Gaza on Tuesday also included two journalists from a Hamas-linked TV channel.
Also late on Tuesday, US Secretary of State Hillary Clinton arrived in Israel, in an effort to support moves towards a ceasefire.
She said she would work with Israel and Egypt on brokering a truce in Gaza "in the days ahead".
After late-night talks with Israeli Prime Minister Benjamin Netanyahu, she is due to travel to Ramallah in the West Bank and Cairo on Wednesday.
The Israeli army said about 150 rockets had been fired from Gaza towards Israel on Tuesday, and many had been intercepted by Israel's Iron Dome missile defence system.
It said one of its soldiers had been killed in the Eshkol area by a rocket - the first military fatality in the recent upsurge.
An Israeli civilian working for the defence ministry was killed by another strike in the Negev desert.
The latest flare-up began last week with the killing of a Hamas military leader. Israel says that assassination, and its subsequent offensive, aims to end rocket fire from Gaza.