Hamas said Wednesday morning that two of its gunmen were killed in a blast in the southern Gaza Strip.
The group says the men were killed on a "holy mission." That's the term Hamas uses when fighters are killed by explosives that go off inadvertently.
Hamas also says that three gunmen killed by Israeli forces on the Gaza border late Tuesday belonged to the group. Their affiliation had not been immediately known.
The clash was the bloodiest since a truce between Israel and Gaza's Islamic Hamas rulers expired over the weekend. It was followed by mortar and rocket attacks from Gaza on southern Israeli border communities late Tuesday and early Wednesday.
Palestinians fired at least 14 rockets and eight mortar shells from the northern Gaza Strip towards the western Negev.