GAZA CITY, Gaza Strip - Palestinian militants sent a deadly barrage of missiles flying deep into Israel yesterday, demonstrating that Hamas still had firepower three days into Israel's punishing air offensive in Gaza.

Four Israelis, including a soldier, were killed and eight wounded. Palestinian health officials put the three-day death toll in Gaza at 364; the United Nations said the total included at least 62 civilians.

Early today (Gaza is seven hours ahead of Philadelphia), Israeli aircraft dropped at least 16 bombs on five Hamas government buildings in a Gaza City complex, destroying them, setting fires and sending rubble flying for hundreds of yards, witnesses said. Rescue workers said 40 people were injured.

In yesterday's attacks, Israel focused its bombing on the houses of Hamas field operatives in a campaign meant to tear at the roots of the extremist group ruling Gaza. Israel's defense minister promised a "war to the bitter end against Hamas" and allied militants.

Intensified rocket strikes by Gaza militants, which triggered the Israeli offensive, have revealed the expanding range of missiles that are making larger cities farther inside Israel vulnerable.

In a barrage last night, a missile crashed into a bus stop in Ashdod, 23 miles from the Gaza Strip. A woman died and two others were wounded, one seriously - the first casualties in the city of 190,000 residents.

Another Israeli was killed and one seriously wounded by a rocket strike in the Negev desert community of Nahal Oz, closer to the Gaza border. Earlier, a missile killed a construction worker in the city of Ashkelon. In all, four Israelis were dead since the Gaza offensive began Saturday, bringing to 19 the number of people killed in attacks from Gaza since the beginning of the year.

The targets chosen by Israel yesterday pointed to an intention to chip away at Hamas' foundation.

A grainy video taken by an Israeli drone airplane showed several men loading a pickup truck with what the Israeli military said were medium-range Grad rockets. Moments later, a big explosion from an Israeli missile strike envelops the image.

Israel's airstrikes on more than 320 sites since midday Saturday reduced dozens of buildings to rubble, overwhelmed hospitals with wounded and filled Gaza's deserted streets with smoke and fire.

Yesterday, aircraft pulverized a house next to the home of Hamas Premier Ismail Haniyeh, a security compound and a five-story building at a university closely linked to the Islamic group - all symbols of Hamas strength in the coastal territory it has ruled since June 2007.

Israel's offensive has rattled the Middle East and capitals around the world, triggering street protests and fiery speeches by adversaries of Israel like the militant group Hezbollah in Lebanon.

Stone-throwing clashes broke out in about a half-dozen spots in the Palestinians' West Bank territory as well as in several Arab-populated areas inside Israel. Israeli police and soldiers fired rubber bullets and tear gas at rioting youths, but it did not appear anyone was injured.

U.N. Secretary-General Ban Ki-moon condemned Israel's offensive as excessive and demanded an immediate cease-fire.

The U.S. government said it was "vigorously engaged" in trying to restore a cease-fire.

A White House spokesman defended the Israeli response, but added that the Bush administration was urging Israel to avoid civilian casualties in Gaza. *