Israel has carried out airstrikes on the Gaza Strip, killing three commanders of the Islamic Jihad militant group and 10 civilians.
Palestinian officials said women and children were among the victims, and that 20 others were injured in the Tuesday's attack.
The Israeli military said the three commanders were responsible for multiple terrorist attacks on Israeli civilians.
Islamic Jihad said in a statement that "We hold the Zionist enemy fully responsible for this treacherous and heinous terrorist massacre," and that the group will "carry out its sacred duties in resisting the enemy."
Islamic Jihad and other Palestinian militants have exchanged attacks with Israel since last month.
Israeli Prime Minister Benjamin Netanyahu has faced intense pressure from his right-wing ministers that he has not done enough to respond to Palestinian rocket attacks.