There has been a fresh round of violence between Palestinian militants in Gaza and Israel, after a ceremony in Washington at which Israel and two Gulf Arab states normalised their relations.
Militants fired two rockets into Israel on Tuesday night. One hit the coastal city of Ashdod, wounding two men.
Another barrage of 13 rockets was launched before dawn on Wednesday.
In retaliation, the Israeli military bombed sites in Gaza it said belonged to the Palestinian group Hamas.
"I'm not surprised that the Palestinian terrorists fired at Israel precisely during this historic ceremony," Israeli Prime Minister Benjamin Netanyahu told reporters before leaving Washington.
"They want to turn back the peace. In that, they will not succeed," he added.
"We will strike at all those who raise a hand to harm us, and we will reach out to all those who extend the hand of peace to us."
Hamas, which controls Gaza, warned Israel that it would "pay the price for any aggression against our people or resistance sites and the response will be direct".
"We will increase and expand our response to the extent that the occupation [Israel] persists in its aggression," it added.
The flare-up started while Mr Netanyahu and the foreign ministers of the United Arab Emirates and Bahrain were on the White House lawn, signing historic normalisation agreements brokered by US President Donald Trump.
Mr Trump said the deals would "serve as the foundation for a comprehensive peace across the entire region".
"After decades of division and conflict we mark the dawn of a new Middle East," he declared.
But the move has deeply angered Palestinians, who accuse the Arab countries of reneging on a promise not to embrace ties with Israel until Palestinian statehood is achieved.
Palestinian Authority President Mahmoud Abbas warned that "peace, security and stability will not be achieved in the region until the Israeli occupation ends".
Before the UAE and Bahrain, the only other Arab countries in the Middle East to recognise Israel officially were Egypt and Jordan, who signed peace treaties in 1978 and 1994 respectively.