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GAZA, May 19 (Reuters) - A rocket-propelled grenade fired by Hamas militants struck an Israeli army bulldozer just inside Gaza's northern border with Israel on Saturday, the militant group said.

It was unclear whether there were any casualties in the attack, the first by Hamas on Israeli positions in Gaza since Israel launched an air campaign against militants on Wednesday.

Israeli ambulances were seen entering the Gaza border near the site of the reported attack.

The Israeli army said it was checking the report.

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