GAZA CITY, Gaza Strip-- The worst violence between Israel and the Gaza Strip in nearly a year entered its second day on Saturday, as Israeli aircraft killed 15 militants, according to Palestinian health officials. Militants responded by firing nearly 100 rockets, seriously wounding an Israeli civilian.

The airstrikes and rocket attacks could drag the volatile area into broader conflict especially if a large number of civilians are killed on either side.

On Saturday, the low whooshing noise of militants firing rockets from border areas toward Israel was palpably heard inside Gaza City. Israeli drones hovered in the skies above. Tens of thousands of Palestinian mourners marched through the streets in funeral processions. They carried slain militants in coffins, their bodies too torn up to be wrapped in cloth, as Muslim tradition dictates. Masked militants sprayed machine gun fire above the mourners' heads in angry grief.

"Revenge, revenge!" chanted the crowds.

On Israel's southern border areas, residents were told to stay home and refrain from holding large outdoor events on Saturday.

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The flare-up began Friday with a strike on militant commander Zuhair al-Qaissi, whom Israel said was planning an attack from the nearby Egyptian Sinai peninsula into the Jewish state. He was the leader of the Popular Resistance Committees, a small group best known for the 2006 abduction of Israeli soldier Gilad Schalit. Schalit was freed last year in exchange for over 1,000 Palestinian prisoners.

It was the highest profile killing Israel has undertaken against militants in the coastal strip in several months.

Gaza militants then unleashed a barrage of rockets toward Israel's southern border communities. One rocket seriously wounded an Israeli civilian and sent families scattering into bomb shelters.

So far, militants have fired 92 rockets. The military said its air defense systems intercepted some 25 rockets before they landed.

In comparison, Palestinian militants fired some 50 rockets toward Israel in the three months preceding the flare up, a military spokesman said. He spoke anonymously in line with military regulations.

Egypt, which has helped arrange truces in the past, said Saturday it was trying to cobble together a cease-fire but hope seemed distant.

Palestinian militants said they would press on, accusing Israel of shattering the months of relative calm in the area.

"(We) won't give this occupation a free truce while our leaders and heroes are being killed," said Abu Mujahid, spokesman for al-Qaissi's group.

Gaza's Hamas rulers condemned the Israeli strike but, pointedly, their militants did not fire rockets at Israel. Instead, they quietly allowed other Palestinian militants to unleash salvos.

In previous flare-ups, Hamas has used such a strategy to allow Palestinian militants to burn off their anger, with an eye toward the exchange of strikes eventually quieting down.

Hamas hasn't been eager to participate in rocket barrages since Israel conducted a punishing three-week war against the militant group that ended in 2009. The air and ground assault killed hundreds of Palestinian civilians and militants, and destroyed much of Hamas' infrastructure.

Since then, Hamas has sought to shore up its Gaza rule and amass a better weapons arsenal.

Still, Israel's military said it Hamas, as the territory's ruler, would "bear the consequences" for any attacks that initiated from Gaza.

Tit-for-tat strikes between Israel and Palestinians are a routine occurrence along the Gaza border. But a flare-up of this intensity has been rare since the 2009 war.

In August, there was flare up when Israel assassinated al-Qaissi's predecessor, Kamal al-Nairab.

But this is the deadliest since April, when 11 Palestinians were killed, including four civilians. In April's flare up, the Israeli strikes came after Palestinian militants fired a rocket that hit a school bus, injuring the driver and badly wounding a 16-year-old boy.

This current round of fighting could spiral out of control if Palestinian militants manage to kill Israeli civilians, prompting a fiercer Israeli response.

Likewise, if an Israeli strike kills Palestinians, or another senior militant member, Hamas may feel forced to join the fray, opening a broader front against Israel.

The Palestinian militants were killed in eight airstrikes overnight and on Saturday morning, said

Gaza health spokesman Adham Abu Salmia. He said some 20 more civilians were wounded by flying shrapnel from the exploding missiles, some of which targeted militants deep in civilian areas of the crowded territory. Another civilian was critically injured when Israeli forces opened fire during the funeral of one of the militants.

The most recent airstrike targeted two Palestinian militants on a motorbike in the border town of Bani Suheila in southeast Gaza, Abu Salmia said.

The flare-up began midmorning Friday, when an Israeli airstrike tore apart al-Qaissi's blue sedan and killed his son-in-law, Mahmoud Hanini, also a PRC commander. Another low-ranking Gaza militant also died.

Some of the militants subsequently killed in Israeli strikes were planning to fire rockets, said Palestinian militant spokespeople. Other militants were targeted, but it wasn't immediately clear why.

The military said al-Qaissi was plotting an infiltration attack into Israel similar to the raid from Egypt's Sinai peninsula that they claim he orchestrated in August, which killed eight Israelis and injured 40 more.

The militant group has never taken responsibility for the attack.

The PRC is responsible for dozens of deadly attacks against Israelis and its members frequently fire rockets into Israel.

Israel often targets Gaza militants it says are preparing attacks, but tensions have been relatively calm in recent months with Israel mostly targeting smuggling tunnels from Egypt.