GAZA CITY, Gaza Strip (WACH/AP) -- The heaviest fighting in four years between Israel and militants in the Gaza Strip has brought life to a standstill on both sides of the border.
Gaza's streets are mostly empty today as the Israeli air force continues to strike targets. Across southern Israel, residents remain huddled in doors or close to home.
Militants in Gaza have been pounding southern Israel with rocket fire today, killing three people.
It's the second day of intense Israeli air raids and naval attacks on militant targets. And Israel is threatening to invade the Palestinian territory.
After yesterday's assassination of Hamas mastermind Ahmed Jabari, Israeli tanks, gunboats and aircraft struck dozens of sites across Gaza. According to Palestinian medical officials, a total of 15 Palestinians, including seven civilians, have been killed, and more than 100 others wounded.
Israel says yesterday's assassination was the start of a broader offensive that was launched after days of rocket fire from Gaza into southern Israel.
Both sides have also taken to social media to advance their cause.
Wednesday the Israel Defense Forces tweeted: "We recommend that no Hamas operatives, whether low level or senior leaders, show their faces above ground in the days ahead."
An account for the Palestinian Alqassam Brigade responded: "Our blessed hands will reach your leaders and soldiers wherever they are (You Opened Hell Gates on Yourselves)."
Israel's prime minister says the army is prepared for a "significant widening" of its operation in the Gaza Strip.
Benjamin Netanyahu told reporters on Thursday that Israel has "made it clear" it won't tolerate continued rocket fire on its civilians.
He says he hopes Hamas has received the message. But if not, he says Israel will take whatever action is necessary to protect its people.
Meanwhile Iran and Egypt have condemned Israel's military assault on the Gaza Strip.
Iranian state TV on Thursday quoted Foreign Ministry spokesman Ramin Mehmanparast as calling the Israeli bombardment of Gaza "organized terrorism."
Egypt's Islamist president has ordered his prime minister to lead a senior delegation to Gaza in a show of support for the coastal strip's Hamas rulers in the face of Israel's offensive.
Egypt has asked the United States to push Israel to stop its offensive against Hamas militants in the Gaza Strip, warning that the violence could "escalate out of control."
In recent years, Hamas has beefed up its arsenal with more powerful and far-reaching missiles. Israel, meanwhile, has deployed a system that shoots down incoming rockets.
(The Associated Press contributed to this report.)