Israel bombarded the Hamas-ruled Gaza Strip with more than 180 airstrikes early Saturday, the military said, widening a blistering assault on militant operations to include the prime minister's headquarters, a police compound and a vast network of smuggling tunnels.
The new attacks followed an unprecedented rocket strike aimed at the contested holy city of Jerusalem that raised the stakes in Israel's violent confrontation with Palestinian militants.
Israeli aircraft also kept pounding their original targets, the militants' weapons storage facilities and underground rocket launching sites. The Israeli military called up thousands of reservists and massed troops, tanks and armored vehicles along the border with Hamas-ruled Gaza, signaling a ground invasion could be imminent.
Militants, undaunted by the heavy damage the Israeli attacks have inflicted, have unleashed some 500 rockets against the Jewish state, including new, longer-range weapons turned for the first time this week against Jerusalem and Israel's Tel Aviv heartland.
Six people, including five militants, were killed and dozens were wounded in the various attacks Saturday, Gaza health official Ashraf al-Kidra said. In all, 35 Palestinians, including 13 civilians, and three Israeli civilians have been killed since the Israeli operation began.
Israel had been slowly expanding its operation beyond military targets but before dawn on Saturday it ramped that up dramatically, hitting Hamas symbols of power. A three-story apartment building belonging to a Hamas military commander was hit, and ambulances ferried out more than 30 inhabitants wounded by the powerful explosion.
Missiles smashed into two small security facilities as well as the massive Hamas police headquarters in Gaza City, setting off a huge blaze that engulfed nearby houses and civilian cars parked outside, the Interior Ministry reported. No one was inside the buildings.
The Interior Ministry said a government compound was also hit while devout Muslims streamed to the area for early morning prayers, although it did not report any casualties from that attack. Also hit was a Cabinet building where the Hamas prime minister has his offices. Prime Minister Ismail Haniyeh was not inside.
Missiles knocked out five electricity transformers, plunging more than 400,000 people in southern Gaza into darkness, according to the Gaza electricity distribution company.
In southern Gaza, Israeli aircraft went after the hundreds of underground tunnels militants used to smuggle in weapons and other contraband from Egypt, residents reported. A huge explosion in the area sent buildings shuddering in the Egyptian city of El-Arish, 30 miles away, an Associated Press correspondent there reported. The tunnels have also been a lifeline for residents of the area during the recent fighting, providing a conduit for food, fuel and other goods after supplies stopped coming in from Israel before the military operation began.
The Israeli military did not provide a detailed accounting of its overnight targets, but said more than 180 sites were struck, for a total of more than 800 since the operation began.
The widened scope of targets brings the scale of fighting closer to that of the war the two groups waged four years ago. Hamas, a group that remains pledged to Israel's destruction, was badly bruised during that confrontation, but has since restocked its arsenal with more and better weapons, and has been under pressure from smaller, more militant groups to prove its commitment to fighting Israel.
The attack aimed at Jerusalem on Friday and two strikes on metropolitan Tel Aviv showcased the militants' new capabilities, including a locally made rocket that appears to have taken Israeli defense officials by surprise. Both areas had remained outside the gunmen's reach before.
Just a few years ago, Palestinian rockets were limited to crude devices manufactured in Gaza. But in recent years, Israeli officials say, Hamas and other armed groups have smuggled in sophisticated, longer-range rockets from Iran and Libya.
The eerie wail of air raid sirens sounded in Jerusalem after the start of the Jewish Sabbath in the holy city, claimed by both Israel and the Palestinians as a capital. Residents were shocked to find themselves suddenly threatened by rocket fire, which, for more than a decade, had been restricted to steadily broadening sections of southern Israel.
The attack was audacious, both for its symbolism and its reach. Located 50 miles from the Gaza border, Jerusalem had been considered beyond the range of Gaza's imprecise rockets — and an unlikely target because it is home to the Al-Aqsa Mosque compound, Islam's third-holiest shrine.
Israeli police spokesman Micky Rosenfeld said the rocket landed in an open area outside the city — near the Palestinian city of Bethlehem and just a few miles from Al-Aqsa.
"We are sending a short and simple message: There is no security for any Zionist on any single inch of Palestine and we plan more surprises," said Abu Obeida, a spokesman for Hamas' armed wing.
Israeli leaders have threatened to widen the operation if the rocket fire doesn't halt. Foreign Minister Avigdor Lieberman said options included the possible assassination of Haniyeh, the prime minister.
Israeli Prime Minister Benjamin Netanyahu met in emergency session with Cabinet ministers Friday. Israeli media reported they approved drafting 75,000 reservists. Earlier this week, the government approved a separate call-up of 30,000.
Lt. Col. Avital Leibovich, a military spokeswoman, said 16,000 reservists were called to duty on Friday and others could soon follow.
She said no decision had been made on a ground offensive but all options are on the table.
President Barack Obama spoke separately to Israeli and Egyptian leaders Friday as the violence in Gaza intensified. In a conversation with Israeli Prime Minister Benjamin Netanyahu, he reiterated U.S. support for Israel's right to self-defense. To Egyptian President Mohammed Morsi, he praised Egypt's efforts to ease regional tensions.