Israel's army on Thursday said it had received a rocket warning in the north of the country, the first time the alert has been given there since hostilities soared between Israel and Palestinians earlier this week.

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The approximately 1,500 rockets fired from Gaza by Hamas militants since Monday had so far set off warnings in southern and central Israel, but not in the north, the army said.

However in the small hours of Thursday morning, alarms not only sounded in the economic capital Tel Aviv in the middle of the country -- where residents rushed to shelters -- but also in Jezreel Valley in the north.

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Since hostilities escalated on Monday evening, Hamas has fired around 1,500 rockets from Gaza into Israeli territory, according to the latest estimate by Israel's army.

The launch of around 350 rockets had failed, while hundreds more were intercepted by Israel's Iron Dome air defence system, the army said.

Seven people in Israel have been killed by the onslaught, including a six-year-old and a soldier.

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Israel's army continued carrying out air strikes on Gaza early Thursday morning, according to an AFP journalist.

The Palestinian health ministry said the death toll from the violence in the territory since Monday has risen to 67 fatalities and 388 injured.