GAZA ATTACK: Israel Intercepts Rocket Blitz After Hit on Hamas

The Israeli military said the some 20 airstrikes were part of a major offensive dubbed "Operation Pillar of Defense," Reuters reports.

"All options are on the table. If necessary, the (Israeli military) is ready to initiate a ground operation in Gaza," it said.

Benjamin Netanyahu says Israel cannot tolerate continued rocket attacks against its citizens. In his first comments since Israel killed the commander of the Hamas military wing, Netanyahu said Israel is "prepared to expand the operation." 

Hamas has responded with threats of retaliation.

"The occupation has opened the gates of hell," the armed wing of Hamas reportedly said.

"Israel has declared war on Gaza and they will bear the responsibility for the consequences," Islamic Jihad reportedly said.

Ahmad Jabari, the commander of military wing of Hamas, was the most senior Hamas official to be killed since the last war in Gaza ended in early 2009. He has long topped Israel's most-wanted list, blamed for a string of deadly attacks, including the kidnapping of Israeli soldier Gilad Schalit in 2006.

The offensive followed a weekend exchange of rocket fire from Gaza on southern Israel and Israeli airstrikes. Seven Palestinians were killed and several Israelis were wounded.

The military said its aircraft targeted more than 20 facilities that served as storage or launching sites for rockets. Among the weapons destroyed were rockets that could hit as far as 25 miles into Israel.

Plumes of black smoke wafted into Gaza City's skies following at least five airstrikes there. Sirens blared as people ran in panic in the streets and militants fired angrily into the air. Hamas police cordoned off the area around a hospital where at least one body from the strike was taken. It was draped in a white sheet, with a burnt leg poking out.