Israel launched an air strike on Wednesday on the northern Gaza Strip, wounding four people, medical officials in the Hamas-ruled territory said.
The Israeli military had no immediate comment on the attack, which came two days after militants in the Palestinian enclave launched rockets into southern Israel.
Earlier, the Gaza-based Islamist group Hamas and President Mahmoud Abbas's Palestine Liberation Organization (PLO) agreed to implement a unity pact, both sides announced in a joint news conference.
The move envisions forming a unity government within five weeks and holding national elections six months after a vote of confidence by the Palestinian parliament.
Palestinians have long hoped for a healing of the political rift between the PLO and militant Hamas, which won a Palestinian election in 2006 and seized control of the Gaza Strip from forces loyal to Western-backed Abbas in 2007.
But Arab-brokered unity pacts reached between the two sides have yet to be implemented, leaving many Palestinians skeptical about their leaders' reconciliation pledges.
"This is the good news we tell our people: the era of division is over," Hamas prime minister Ismail Haniyeh told Palestinian reporters to loud applause.
Hamas has repeatedly battled Israel, which it refuses to recognise. Before Wednesday's announcement, Israeli Prime Minister Benjamin Netanyahu cautioned Abbas over the unity efforts, saying he had to choose between peace with Israel or its Islamist enemy.
Abbas's Fatah party has remained in control of the Palestinian Authority in the occupied West Bank and pursued troubled peace talks with Israel, which are set to expire on April 29.