The deadly exchange of fire between Palestinian militants in the Gaza Strip and the Israeli military has escalated significantly, with the UN fearing a “full-scale war”.
More than 1,000 rockets have now been fired by Palestinian militants over 38 hours, Israel said, most at Tel Aviv.
Israel has carried out deadly air strikes, bringing down two tower blocks in Gaza on Tuesday.
Israeli Arabs have also staged violent protests in a number of Israeli towns.
The city of Lod, near Tel Aviv, has been put under a state of emergency.
UN Secretary-General António Guterres said he was “gravely concerned” by the ongoing violence.
Six Israelis have died and in Gaza at least 43 Palestinians, including 13 children, have been killed since Monday, the health ministry said.
The latest fatality was an Israeli citizen, who was killed when an anti-tank guided missile, fired from the northern Gaza Strip, struck a jeep on the border. Two other people were injured.
The fighting follows weeks of rising tension stoked by violent confrontations between Israeli police and Palestinian protesters at a site in Jerusalem that is holy to both Muslims and Jews.