In the densely populated Gaza Strip, on Wednesday, explosions echoed day and night, shaking buildings and sending up plumes of smoke, at least 17 civilians including five children were among the 23 dead, Palestinian officials said.
Israelis escaped on Tuesday, as air-raid sirens sounded in the business capital, Tel Aviv and the holy city of Jerusalem, both of which were hit in the Gaza war of November 2012.
Israelis Iron Dome interceptor shot down a rocket fired at Tel Aviv by Gaza faction Islamic Jihad, Israel said this may be just the start of a lengthy offensive against Islamist militants whose rockets struck deeper than ever before into Israel.
Hamas said it also fired a rocket at the major Northern City of Haifa, 140 km (88 miles) away, though this was not confirmed, Israel said a rocket had landed in Hadera, 100 km (60 miles) from Gaza, further than had previously been reached.
The rocket strikes could lead to an Israeli ground invasion, something officials have said is a possible option.
The militant, Hafez Hamad, two brothers and his parents were killed when his house was bombed in an air strike in the town of Beit Hanoun in the northern Gaza Strip, Hamas Media and Gaza Interior Ministry said. An unidentified woman in the house was also killed.
Since Israel launched its offensive on Tuesday, five Hamas gunmen, an Islamic Jihad leader and 17 civilians, including seven children, have been killed.
Prime Minister, Benjamin Netanyahu, called on Israelis to rally together and “show resilience because this operation could take time”.
“We will not tolerate rocket fire against our cities and townships, and therefore I ordered a significant broadening of IDF (Israel Defence Force) operations against the terrorists of Hamas and other terror groups in the Gaza Strip,” he said in a statement.
In a bold infiltration, gunmen from Hamas landed on the shore near Zikim, adjacent to the Gaza border, where a kibbutz and a military base are located. Four gunmen were killed.
Palestinians have since launched more than 200 rockets from Gaza, Israel said.
While threatening an “earthquake” of escalation against Israel, Hamas said it could restore calm if Israel halted the Gaza offensive, once again committed to a 2012 Egyptian-brokered truce and freed prisoners it detained in the West Bank last month.
The Israeli military said on Tuesday that, to support regular forces, it had called up 1,000 reserve troops out of a pool of 40,000 approved by the security cabinet. Some 1,500 other reservists have already been mobilised.