Gaza, Sep 14 : At least five Palestinians were killed in a blast at the Israel-Gaza border, the Hamas-run Health Ministry in Gaza said. The explosion that took place during a mass demonstration of the Palestinians injured 25 others, it added on Wednesday. Before the blast, there was a clash between dozens of Palestinian protestors and Israeli soldiers along the border fence, during which Israeli soldiers fired live bullets and tear gas bombs, Palestinian security sources and eyewitnesses said. The Israel Defense Forces (IDF) said Israeli soldiers used dispersal measures after the Palestinians hurled explosive devices and grenades at the barrier, according to The Times of Israel. Investigation is underway to find the cause of the explosion, but the IDF claimed an explosive device was placed by the Palestinian "rioters" during the demonstration in an attempt to hurt Israelis, Xinhua news agency reported. Meanwhile, the Israeli Army denied the possibility that Israeli gunfire caused the explosion, saying that the device exploded on its own during an attempt to throw it. /IANS