GAZA, March 12 (Nidal al-Mughrabi/Reuters & JMCC) - Israeli air strikes killed two Palestinian militants and a civilian in the Gaza Strip on Monday in a fourth day of hostilities, medical sources said.

The latest violence followed a familiar pattern in which militants launch rocket attacks and Israel carries out air strikes in the Hamas-controlled enclave. But the bloodshed has usually ended after a few days with an informal truce.

Gaza's Hamas leadership, whose own cadres have kept out of the fighting, said on Sunday that neighboring Egypt was working to stop the violence and consulting with other militants. But Hamas said Israel must first stop its air strikes.

A Palestinian official close to the mediation told Reuters that Israel had agreed to a midnight ceasefire. But Islamic Jihad - an Iranian-backed faction responsible for most the rocket fire - had baulked and intensified its attacks overnight.

Israeli military spokesman Brigadier-General Yoav Mordechai said officials were in contact Egypt over a truce. But Israeli forces will still hit at Islamic Jihad and Israel saw Hamas as responsible for everything that took place in Gaza, he said.

An Islamic Jihad gunman was killed on Monday while launching a rocket from south Gaza, the group said. Another died and three others were hurt when their motorized rickshaw was hit.

Hamas and hospital officials said a 15-year-old schoolboy was killed in a separate air strike on Monday. At least 28 other Palestinian civilians were wounded in the various incidents.

Palestinian attacks have disrupted normal life in southern Israel, forcing many schools to close on Sunday and Monday. Israeli aircraft have flown over Gaza since Friday, killing at least 21 people, including two civilians.

PAINFUL BLOW

The Israeli military had no immediate comment on the slain schoolboy but said the air force had struck repeatedly in Gaza overnight in response to more than 20 rocket launches.

Islamic Jihad and the Popular Resistance Committees, armed groups largely independent of Hamas, have said they fired most of the rockets launched at Israel since Friday.

Israeli Defense Minister Ehud Barak predicted in a statement on Sunday that it would take several more days until the violence ended and Prime Minister Benjamin Netanyahu said Israel would hit hard at militants who launched rockets at its towns.

Though serious, few in Israel expect the bloodshed to lead to a ground assault reminiscent of the 2008-2009 Gaza war in which some 1,400 Palestinians and 13 Israelis were killed.

Israel is not keen to see an escalation, Israel is not keen to hurt innocents - Israel is absolutely opposed to this, said Interior Minister Eli Yishai told Israeli Army Radio.

For now, it (fighting) is on this kind of scale. But if it will prove protracted, then without a doubt there will be a powerful, painful blow so that this will not continue, he said.

The latest round of violence flared on Friday when an air strike killed two Palestinian militant leaders in Gaza accused by Israel of planning a cross-border attack via Egypt. A salvo of rockets followed, wounding six people in Israel.

The densely packed enclave, home to 1.7 million people, has been under Israeli occupation since 1967 and remains under an Israeli blockade.

Hamas has controlled Gaza since 2007 and is fighting for an independent Palestinian state but has stayed away from the stalled peace process supervised by international powers and refuses to recognize the state of Israel.

The Islamic Jihad is less influential than Hamas but shares the same Islamist ideology.

(Writing by Ori Lewis; Editing by Angus MacSwan)