Israeli military officials said none of the missiles fired from Gaza landed in Tel Aviv, but a spokesman cautioned people living in central Israel to prepare for a night that "won't be calm," Haaretz reported. Israeli television reports said Defense Minister Ehud Barak has authorized the army to call up 30,000 reservists to take part in the operation in Gaza.
The attack on Tel Aviv was the first since the Gulf War, more than 20 years ago, The Jerusalem Post reported.
A group of hackers identifying themselves as "Anonymous" attacked an undetermined number of Israeli websites Thursday -- including military and financial websites -- saying the attacks were in retaliation for the operation in Gaza, Haaretz said.
Israel launched Operation Pillar of Defense with an airstrike Wednesday that killed Ahmed al-Jabari, Hamas' military leader. By late Thursday, 250 rockets had been fired into Israel from Gaza in retaliation.
Jabari, commander of the al-Qassam Brigades, was in a car hit by an Israeli missile.
Residents of Tel Aviv could hear rockets landing not long after air raid sirens sounded, Ynetnews.com reported. The rockets hit about 10 miles south of the country's second-largest city.
The three Israeli deaths occurred in Kiryat Malachi, 11 miles northeast of Ashkelon, when a rocket struck an apartment building. Fifteen Palestinians have been killed in the fighting, The Washington Post said.
Iron Dome missile defense systems deployed in southern Israel intercepted at least 70 rockets, the army said. The Israeli air force has struck more than 100 militant targets and rocket stockpiles in Gaza, the army said.
Israeli troops and tanks massed on the Gaza border prepared for a possible ground invasion but Dichter refused to comment on whether the army would conduct a ground operation in addition to the airstrikes.
"The aim of the operation is to destroy the large stockpiles of rockets in Gaza and bring a complete halt to rocket fire on Israel. The army is prepared," Dichter said.
Broadcasts on Israel's national radio station Thursday were often interrupted with warnings of incoming rocket fire in southern areas. Rockets fell in Beersheba, Ashkelon, Ashdod, Kiryat Malachi, Netivot, Gan Yavne and other Israeli communities near the Gaza Strip.
Israeli civil defense authorities instructed residents within a 25-mile radius of Gaza not to go to school or work Thursday. At least 1 million Israelis stayed in bomb shelters overnight, the military said on Twitter Thursday.
Thousands of people participated in al-Jabari's funeral at noon Thursday. His body, covered in Hamas colors, was first taken to his home and then to a local mosque for prayers before setting out for the cemetery.
Hamas, a Palestinian Sunni Islamist sociopolitical organization that governs the Gaza Strip and has a military wing called the Izz ad-Din al-Qassam Brigades, said Israelis "opened the gates of hell upon themselves" with the attack.
But leaders of Hamas and other militant organizations in Gaza are in hiding in fear they will be targeted by Israel, Israel Radio said.
The escalation in hostilities prompted Egypt to recall its ambassador and demand meetings of the U.N. Security Council and the Arab League. Israel's ambassador to Egypt returned to Israel Wednesday evening.
The Muslim Brotherhood called on Egyptian President Mohamed Morsi to sever diplomatic and trade ties with Israel, Israel Radio said.
U.S. President Barack Obama spoke with Netanyahu and Morsi, the White House said Wednesday night.
Obama told both leaders the United States supported Israel's right to self-defense from rocket attacks, the White House said in a statement.
The statement said Obama and Netanyahu "agreed that Hamas needs to stop its attacks on Israel to allow the situation to de-escalate." It said Obama urged Netanyahu to "make every effort to avoid civilian casualties."
Obama told Morsi Washington condemned the rocket fire.
The United States and Israel classify Hamas as a terrorist organization.
The U.N. Security Council had an emergency meeting Wednesday night to discuss the airstrikes but took no substantive action. Council President and Indian Ambassador Hardeep Singh Puri said after the 90-minute closed-door meeting council members would issue a communique stating the emergency meeting took place.