The incidents marked the third straight day in which Palestinians in Gaza fired at IDF soldiers on the border.Hamas launched a series of cross-border mortar attacks targeting IDF units on the border with northern and southern Gaza on Wednesday, prompting the IDF to return fire with tanks, and later air strikes on Hamas targets. The escalation - the most significant since the August 2014 cease-fire that ended a two-month conflict - came as Hamas sought to disrupt IDF work to detect its attack tunnels.On Tuesday, Hamas directed cross-border gun fire at an IDF engineering vehicle near southern Gaza.There were no injuries in this week's incidents.