The militant group said the vehicles were hit as they headed away from Gaza City on Friday after the army ordered more than a million residents to evacuate to the south of the besieged territory ahead of an expected ground invasion.

Sky News has seen footage that appears to show a low-loader, carrying scores of people, both before and in the devastating aftermath of the explosion, which has been blamed on Israel.

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It was not immediately clear who the target was, or whether insurgents were among the passengers.

Responding, Lieutenant Colonel Peter Lerner of the Israeli Defence Force (IDF) told Sky News: "I am not aware of any IDF strikes at this time at that location, but we will be updating throughout the day."

Pressed over the implications if it was shown Israel was responsible, Lt Col Lerner stressed the need to establish the facts first.

He said: "We need to be very clear what exactly happened and we also need to be aware that Hamas is booby trapping roads.

"They could be doing it themselves. Who knows? We don't.

"We need to be very, very cautious in judging before we know the facts."

It is a week since Hamas launched a deadly surprise attack on Israel triggering a conflict that has already claimed more than 3,200 lives on both sides.

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The Israeli military has said "hundreds of thousands" of Palestinians have already crossed the Wadi Gaza - a piece of coastal wetland with a river running through the middle - into the southern part of the Gaza Strip.

But Hamas has told people to ignore the evacuation order.

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Israel has said it wants to target insurgent strongholds, but Palestinians and some Egyptian officials fear the ultimate aim is to push Gazans out through the southern border with Egypt.

The mass exodus came despite warnings from the United Nations and aid groups such a forced evacuation would have devastating humanitarian consequences, with hospital patients and others unable to move.