Two Palestinians were killed on Wednesday in an explosion in a house in the Zeitun neighborhood of Gaza City, Palestinian eyewitnesses said.
The explosion ripped through the house of the Dahdouh family whose sons are members of the Islamic Jihad. Two family members were killed in an Israeli air strike.
The IDF has denied involvement while Palestinian sources said the explosion was caused by a work accident.
Three people were critically injured in the explosion.
The sources added the two brothers were probably preparing an explosive device which prematurely detonated.
The IDF meanwhile continued its operations in northern Gaza and exchanges of fire between soldiers and gunmen were heard in the Beit Hanun area.
Hamas gunmen hurled explosive devices at IDF troops.
Palestinian medical sources told Ynet that an 11-year-old Palestinian boy was shot in the face by IDF soldiers near the Erez crossing. Doctors said the youth was in critical condition.
Hamas vows more attacks
Meanwhile, Hamas' military wing threatened a severe response to Israel's continued operations in Gaza. Hamas officials said should Israel harm the group's leaders they will bring their struggle to the streets of Israel.
Officials said the unprecedented firing of a Qassam rocket into Ashkelon on Tuesday night will be followed by "more surprises."
A senior Hamas official said the group will continue attacks against strategic sites in Israel.
Hanan Greenberg contributed to this report