GAZA, Nov. 15 (UPI) -- A rocket struck an apartment building in Israel, killing three people, and the Israeli military operation against the Gaza Strip entered its second day.

More than 220 rockets were fired at southern Israel since Wednesday's start of Operation Pillar of Defense with the killing of Hamas military commander Ahmed al-Jabari, who was targeted as he rode in his car, the Israeli army 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 Minister of Homeland Security Avi Dichter said the Israeli operation is expected to last many days. Speaking on Israel Radio, Dichter refused to comment on whether the army would conduct a ground operation in addition to airstrikes on rocket stockpiles and other targets in the Gaza Strip.

However, Israeli troops and tanks massed on the Gaza border prepared for a possible ground invasion.

"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 in southern areas of incoming rocket fire.

In Kiryat Malachi, three Israelis were killed and six injured when an apartment building was hit by rockets from Gaza. 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.

At least 12 people, including three Hamas operatives, have been killed in Gaza since the airstrikes began. The BBC said civilians, including the 11-month-old son of a BBC employee, were among the dead.

At noon, thousands of people participated in al-Jabari's funeral. His body covered in Hamas colors was first taken to his home and from there 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 Mohammed Morsi to sever diplomatic and trade ties with Israel, Israel Radio said.

U.S. President Barack Obama spoke with Israeli Prime Minister Binyamin 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 two leaders agreed on the importance of working to de-escalate the situation as quickly as possible," the White House said.

Morsi had called the Israeli actions "wanton aggression on the Gaza Strip."

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.

U.N. Secretary-General Ban Ki-moon's office said earlier he spoke by phone with Netanyahu and Morsi about the "deteriorating situation." Ban told Netanyahu he was concerned about "an alarming escalation of indiscriminate rocket fire from Gaza into Israel and the targeted killing by Israel of a Hamas military operative in Gaza," his office said.

He encouraged Morsi "to prevent any further deterioration," the office said.