Israeli helicopters could be heard firing and at least two big explosions were heard from the western and northern parts of the city, he added.
The Israeli onslaught continues as diplomatic manoeuvres by various parties - from this week's UN Security Council resolution calling for a ceasefire to Egyptian attempts to broker a truce - have failed to stop the violence.
Al Jazeera has learnt that the UN General Assembly plans to hold an emergency session, but not until Thursday.
Public support
Al Jazeera's Zeina Awad, reporting from the Israeli side of the Gaza border, said the Israeli public was still largely supportive of the military campaign as the general feeling was that it was going very much in Israel's favour.
The view is that the longer the offensive goes on, the better for Israel as it creates "facts on the ground", weakening Hamas's infrastructure and very likely weakening its negotiating position for any ceasefire agreement, our correspondent said.
On Tuesday, Ismail Haniya, the depose Palestinian prime minister and Hamas leader, called for a ceasefire without mentioning the group's long-held demand that Israel lift its blockade of the territory, although it remained unclear if this was a softening of Hamas's stance, our correspondent added.
Israel says 10 Israeli soldiers and three civilians hit by Hamas rockets have been killed so far in the campaign, a casualty rate that the Israeli public seems willing to accept, our correspondent said.
Around 970 Palestinians have been killed, including some 400 women and children, and 4,300 have been wounded.
'Test of our humanity'
The senior UN aid official for Gaza appealed to the international community to protect Gaza's civilians, saying nowhere in the territory of 1.5 million people was safe any longer with the conflict becoming "a test of our humanity".
"All the people, the first thing they say to me and the last thing they say to me is 'Please, we need protection, nowhere is safe'," John Ging, the director of operations for the UN Relief and Works Agency, told reporters.
His plea came as the town of Rafah near the Egyptian border suffered extensive Israeli bombardment causing several thousand residents to flee their homes on Tuesday.
Israel is using "bunker-busting" bombs in an attempt to destroy underground tunnels it says have been used to smuggle weapons and goods into the blockaded Gaza Strip.
Ayman Mohyeldin, Al Jazeera's correspondent in Gaza, said tens of thousands of Palestinians had fled their homes after the Israeli military dropped leaflets warning them of intensive air strikes.
"A large part of Rafah has been completely reduced to rubble... it has been described as hell on earth by some of the witnesses we have met," he said.