The humanitarian gesture of allowing in aid shipments proved short-lived, say observers on the ground in Gaza. Earlier today, Israeli war planes and combat helicopters pounded the area, killing around 200 people.
News agencies report that the dead and wounded lay scattered on the ground following the Israeli attacks, which destroyed several Hamas police compounds in the bloodiest day for Palestinians in more than 20 years.
Distraught rescuers cried out as they tried to find those still alive and black smoke billowed over Gaza city, a Reuters communique says.
The Israeli military describes its action as a "massive attack" targeting the "terrorist infrastructure" of the Hamas-ruled Gaza Strip.
Hospital officials in Gaza City say more than 155 people have been killed there, including 40 at a police headquarters where a graduation ceremony for new recruits was being held. Among those killed was police chief Tawfiq Jabber.
Another 23 Palestinians were killed in air strikes in Khan Younis and Rafah in the southern Gaza Strip, medical officials said. At one site, there was a huge crater in the ground.
Rescuers carried those showing signs of life to cars and ambulances, while others tried to revive the unconscious.
The assualt follws the collapse of a six-month-old, Egyptian-brokered ceasefire just over a week ago.
Gaza militants have fired dozens of makeshift rockets at southern Israel in recent days. The rockets cause damage but few injuries.
In a response to the Israeli attack this morning, one Israeli settler is reported dead.
But Hamas armed wing spokesperson Abu Ubaida has now threatened to unleash "hell" on Israel, saying the Islamist group would "teach the enemy a lesson they will never forget."
Hamas said it was considering a new suicide bombing campaign as a result of the air strikes.
Israeli security officials say that they will respond to this with more attacks on an even larger scale.
The cycle of violence seems unremitting.