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An Israeli airstrike killed a senior militant in Gaza Monday as Hamas fighters fired hundreds of rockets at Israel -- but both sides say its up to the other to end the fighting that has killed at least 100 people and wounded hundreds on both sides of the conflict.

An Israeli missile strike on a high-rise media center in Gaza killed Ramez Harb, a senior figure in Islamic Jihad's military wing, the Al Quds Brigades, the group said in a text message to reporters. Israel has escalated its bombing campaign and began attacking homes of activists in Hamas over the weekend.

Meanwhile, Israel's Iron Dome reportedly intercepted 29 rockets Monday alone -- the defense system has intercepted hundreds of rockets since Operation "Pillar of Defense" began six days ago.

Egypt is leading the efforts to mediate a cease-fire between Israel and Hamas, but both sides are far apart in their demands.

Hamas leader Khaled Meshaal said at a press conference Monday in Egypt that Palestinian weapons had caught Israel "off guard."

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"Whoever started the war must end it," Meshaal reportedly said.

An Israeli official said Israel hoped to find a diplomatic solution to the crisis and signaled Egypt was likely to play a key role in enforcing any truce.

"We prefer the diplomatic solution if it's possible. If we see it's not going to bear fruit, we can escalate," he said, speaking on condition of anonymity because of the sensitive diplomatic efforts underway.

The official said Israel doesn't want a "quick fix" that will result in renewed fighting months down the road. Instead, Israel wants "international guarantees" that Hamas, the Islamic militant group that rules Gaza, will not rearm or use Egypt's neighboring Sinai peninsula for militant activity.

Egypt has been trying to broker a cease-fire, with the help of Turkey and Qatar. Turkish Foreign Minister Ahmet Davutoglu and a delegation of Arab foreign ministers were expected in Gaza on Tuesday.

A senior Egyptian official told The Associated Press on Monday that Hamas and Israel were each presenting Egypt with their conditions for a cease-fire.

"I hope that by the end of the day we will receive a final signal of what can be achieved," said the official, who is familiar with the indirect negotiations. He said Israel and Hamas are both looking for guarantees to ensure a long-term stop to hostilities. The official says Egypt's aim is to stop the fighting and "find a direct way to lift the siege of Gaza."

The official spoke on condition of anonymity because of the sensitivity of the indirect negotiations.

Overall, the offensive that began Wednesday killed 100 Palestinians, including 53 civilians, and wounded some 840 people, including 225 children, Gaza heath official Ashraf al-Kidra said.

On the Israeli side, three civilians have died from Palestinian rocket fire and dozens have been wounded. A rocket-defense system has intercepted hundreds of rockets bound for populated areas.

Hamas fighters have fired more than 1,000 rockets into Israel in the current round of fighting, including 95 on Monday, among them one that hit an empty school in the coastal city of Ashkelon. Israeli police spokesman Micky Rosenfeld said 29 rockets were intercepted by the Iron Dome anti-missile battery. Rockets landed in open areas of Beersheva, Ashdod, Ashkelon, and caused damage in a number of areas.

Schools in southern Israel have been closed since the start of the offensive on Wednesday, and large police units deployed in the area to respond to any potential damage and injuries from rockets.

Also Monday, Israel bombarded the remains of the former national security compound in Gaza City. Flying shrapnel killed one child and wounded others living nearby, al-Kidra said. Five farmers were killed in two separate strikes, al-Kidra said, including three who he said had been mistakenly identified earlier by Hamas security officials as Islamic Jihad fighters.

Other strikes killed two fighters on a motorcycle in southern Gaza and two passengers in a taxi that had put a press sign in the windshield, al-Kidra said.

Israel launched the current offensive after months of intensifying rocket fire from the Gaza Strip, which has continued despite the strikes.

In the night from Sunday to Monday, aircraft targeted about 80 militant sites, including underground rocket-launching sites, smuggling tunnels and training bases, as well as Palestinian command posts and weapons storage facilities located in buildings owned by militant commanders, the Israeli military said in a release. Aircraft and gunboats joined forces to attack Hamas police headquarters, and Palestinian rocket squads were struck as they prepared to fire, the release said.

In all, 1,350 targets in the Gaza Strip have been struck since the Israeli operation began. However, military activity over the past two nights has dropped off as targets change and international efforts to wrest a cease-fire plod ahead.

Israel and Hamas have put forth widely divergent conditions for a truce. But failure to end the fighting threatens to touch off an Israeli ground invasion, for which thousands of soldiers, backed by tanks and armored vehicles, have already been mobilized and dispatched to Gaza's border.

President Barack Obama said he was in touch with players across the region in hopes of halting the fighting. While defending Israel's right to defend itself against the rocket fire, he also warned of the risks the Jewish state would take if it were to expand its air assault into a ground war.

"If we see a further escalation of the situation in Gaza, the likelihood of us getting back on any kind of peace track that leads to a two-state solution is going to be pushed off way into the future," Obama said.

The Associated Press contributed to this report.